Upcoming SlideShare
×

Like this presentation? Why not share!

# Beginning algebra

## on Mar 09, 2013

• 3,438 views

### Views

Total Views
3,438
Views on SlideShare
3,437
Embed Views
1

Likes
0
57
0

### 1 Embed1

 http://dev.algebrahub.com 1

### Report content

• Comment goes here.
Are you sure you want to

## Beginning algebraPresentation Transcript

• miL28711_fm_i-xxvi 12:12:06 10:07am Page i BA CONFIRMING PAGES Beginning ALGEBRA Second Edition Julie Miller Daytona Beach Community College Molly O’Neill Daytona Beach Community College Nancy Hyde Formerly of Broward Community College With Contributions by Mitchel Levy
• miL28711_fm_i-xxvi 11:16:2006 12:21 Page iii BA CONFIRMING PAGES Contents Preface xi Chapter R Reference 1 R.1 Study Tips 2 R.2 Fractions 6 R.3 Decimals and Percents 22 R.4 Introduction to Geometry 32 Chapter 1 The Set of Real Numbers 49 1.1 Sets of Numbers and the Real Number Line 50 1.2 Order of Operations 61 1.3 Addition of Real Numbers 71 1.4 Subtraction of Real Numbers 80 Problem Recognition Exercises—Addition and Subtraction of Signed Numbers 88 1.5 Multiplication and Division of Real Numbers 89 1.6 Properties of Real Numbers and Simplifying Expressions 100 Chapter 1 Summary 113 Chapter 1 Review Exercises 117 Chapter 1 Test 119 Chapter 2 Linear Equations and Inequalities 121 2.1 Addition, Subtraction, Multiplication, and Division Properties of Equality 122 2.2 Solving Linear Equations 133 2.3 Linear Equations: Clearing Fractions and Decimals 142 2.4 Applications of Linear Equations: Introduction to Problem Solving 149 2.5 Applications Involving Percents 164 2.6 Formulas and Applications of Geometry 171 2.7 Linear Inequalities 182 Chapter 2 Summary 197 Chapter 2 Review Exercises 203 Chapter 2 Test 206 Cumulative Review Exercises, Chapters 1–2 207 iii
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page iv BA CONFIRMING PAGES iv Contents Chapter 3 Graphing Linear Equations in Two Variables 209 3.1 Rectangular Coordinate System 210 3.2 Linear Equations in Two Variables 221 3.3 Slope of a Line 238 3.4 Slope-Intercept Form of a Line 253 3.5 Point-Slope Formula 264 3.6 Applications of Linear Equations 273 Chapter 3 Summary 284 Chapter 3 Review Exercises 288 Chapter 3 Test 292 Cumulative Review Exercises, Chapters 1–3 294 Chapter 4 Systems of Linear Equations and Inequalities in Two Variables 297 4.1 Solving Systems of Equations by the Graphing Method 298 4.2 Solving Systems of Equations by the Substitution Method 310 4.3 Solving Systems of Equations by the Addition Method 320 4.4 Applications of Linear Equations in Two Variables 331 4.5 Linear Inequalities in Two Variables 341 4.6 Systems of Linear Inequalities in Two Variables 349 Chapter 4 Summary 357 Chapter 4 Review Exercises 362 Chapter 4 Test 366 Cumulative Review Exercises, Chapters 1–4 368 Chapter 5 Polynomials and Properties of Exponents 371 5.1 Exponents: Multiplying and Dividing Common Bases 372 5.2 More Properties of Exponents 382 5.3 Definitions of b0 and b؊n 387 5.4 Scientific Notation 395 Problem Recognition Exercises—Properties of Exponents 404 5.5 Addition and Subtraction of Polynomials 404 5.6 Multiplication of Polynomials 416 5.7 Division of Polynomials 426 Problem Recognition Exercises—Operations on Polynomials 434 Chapter 5 Summary 435 Chapter 5 Review Exercises 438 Chapter 5 Test 441 Cumulative Review Exercises, Chapters 1–5 442
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page v BA CONFIRMING PAGES Contents v Chapter 6 Factoring Polynomials 445 6.1 Greatest Common Factor and Factoring by Grouping 446 6.2 Factoring Trinomials of the Form x2 ϩ bx ϩ c (Optional) 456 6.3 Factoring Trinomials: Trial-and-Error Method 462 6.4 Factoring Trinomials: AC-Method 473 6.5 Factoring Binomials 482 6.6 General Factoring Summary 490 6.7 Solving Equations Using the Zero Product Rule 495 Chapter 6 Summary 509 Chapter 6 Review Exercises 513 Chapter 6 Test 515 Cumulative Review Exercises, Chapters 1–6 516 Chapter 7 Rational Expressions 517 7.1 Introduction to Rational Expressions 518 7.2 Multiplication and Division of Rational Expressions 528 7.3 Least Common Denominator 534 7.4 Addition and Subtraction of Rational Expressions 542 Problem Recognition Exercises—Operations on Rational Expressions 552 7.5 Complex Fractions 553 7.6 Rational Equations 561 Problem Recognition Exercises—Comparing Rational Equations and Rational Expressions 571 7.7 Applications of Rational Equations and Proportions 572 7.8 Variation (Optional) 584 Chapter 7 Summary 594 Chapter 7 Review Exercises 599 Chapter 7 Test 602 Cumulative Review Exercises, Chapters 1–7 603 Chapter 8 Radicals 605 8.1 Introduction to Roots and Radicals 606 8.2 Simplifying Radicals 619 8.3 Addition and Subtraction of Radicals 629 8.4 Multiplication of Radicals 636 8.5 Rationalization 643 Problem Recognition Exercises—Operations on Radicals 650 8.6 Radical Equations 651 8.7 Rational Exponents 658
• miL28711_fm_i-xxvi 10/6/06 12:54 AM Page vi BA CONFIRMING PAGES vi Contents Chapter 8 Summary 666 Chapter 8 Review Exercises 670 Chapter 8 Test 673 Cumulative Review Exercises, Chapters 1–8 674 Chapter 9 Functions, Complex Numbers, and Quadratic Equations 677 9.1 Introduction to Functions 678 9.2 Complex Numbers 693 9.3 The Square Root Property and Completing the Square 702 9.4 Quadratic Formula 711 9.5 Graphing Quadratic Functions 721 Chapter 9 Summary 734 Chapter 9 Review Exercises 737 Chapter 9 Test 741 Cumulative Review Exercises, Chapters 1–9 742 Student Answer Appendix SA–1
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page vii BA CONFIRMING PAGES Dedication To our students . . . —Julie Miller —Molly O’Neill —Nancy Hyde
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page viii BA CONFIRMING PAGES About the Authors Julie Miller Julie Miller has been on the faculty of the Mathematics Department at Daytona Beach Community College for 18 years, where she has taught developmental and upper-level courses. Prior to her work at DBCC, she worked as a software engineer for General Electric in the area of flight and radar simulation. Julie earned a bachelor of science in applied mathematics from Union College in Schenectady, New York, and a master of science in mathematics from the Uni- versity of Florida. In addition to this textbook, she has authored several course supplements for college algebra, trigonometry, and precalculus, as well as several short works of fiction and nonfiction for young readers. “My father is a medical researcher, and I got hooked on math and science when I was young and would visit his laboratory. I can remember using graph paper to plot data points for his experiments and doing simple calculations. He would then tell me what the peaks and features in the graph meant in the context of his experiment. I think that applications and hands-on experience made math come alive for me and I’d like to see math come alive for my students.” —Julie Miller Molly O’Neill Molly O’Neill is also from Daytona Beach Community College, where she has taught for 20 years in the Mathematics Department. She has taught a variety of courses from developmental mathematics to calculus. Before she came to Florida, Molly taught as an adjunct instructor at the University of Michigan–Dearborn, Eastern Michigan University, Wayne State University, and Oakland Community College. Molly earned a bachelor of science in mathematics and a master of arts and teaching from Western Michigan Uni- versity in Kalamazoo, Michigan. Besides this textbook, she has authored several course supplements for college algebra, trigonometry, and precalculus and has reviewed texts for devel- opmental mathematics. “I differ from many of my colleagues in that math was not always easy for me. But in seventh grade I had a teacher who taught me that if I follow the rules of mathematics, even I could solve math problems. Once I un- derstood this, I enjoyed math to the point of choosing it for my career. I now have the greatest job because I get to do math everyday and I have the oppor- tunity to influence my students just as I was influenced. Authoring these texts has given me another avenue to reach even more students.” —Molly O’Neill viii
• miL28711_fm_i-xxvi 10/6/06 04:31 AM Page ix BA CONFIRMING PAGES About the Authors ix Nancy Hyde Nancy Hyde served as a full-time faculty member of the Mathematics Department at Broward Community College for 24 years. During this time she taught the full spectrum of courses from developmental math through dif- ferential equations. She received a bachelor of science degree in math education from Florida State University and a mas- ter’s degree in math education from Florida Atlantic Univer- sity. She has conducted workshops and seminars for both students and teachers on the use of technology in the class- room. In addition to this textbook, she has authored a graph- ing calculator supplement for College Algebra. “I grew up in Brevard County, Florida, with my father working at Cape Canaveral. I was always excited by mathematics and physics in relation to the space program. As I studied higher levels of mathematics I became more intrigued by its abstract nature and infinite possibilities. It is enjoyable and rewarding to convey this perspective to students while helping them to under- stand mathematics.” —Nancy Hyde Mitchel Levy Mitchel Levy of Broward Community College joined the team as the exercise consultant for the Miller/O’Neill/Hyde paperback series. Mitchel received his BA in mathematics in 1983 from the State University of New York at Albany and his MA in mathematical statistics from the University of Maryland, College Park in 1988. With over 17 years of teaching and extensive reviewing experience, Mitchel knows what makes exercise sets work for students. In 1987 he received the first annual “Excellence in Teaching” award for graduate teaching assistants at the University of Maryland. Mitchel was honored as the Broward Community College Professor of the year in 1994, and has co-coached the Broward math team to 3 state championships over 7 years. “I love teaching all level of mathematics from Elementary Algebra through Calculus and Statistics.” —Mitchel Levy
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page x BA CONFIRMING PAGES x Introducing . . . The Miller/O’Neill/Hyde Series in Developmental Mathematics Miller/O’Neill/Hyde casebound series Beginning Algebra, 2/e Intermediate Algebra, 2/e Beginning and Intermediate Algebra, 2/e Miller/O’Neill/Hyde worktext series Basic College Mathematics Introductory Algebra Intermediate Algebra x
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page xi BA CONFIRMING PAGES Preface From the Authors First and foremost, we would like to thank the students and colleagues who have helped us prepare this text. The content and organization are based on a wealth of resources. Aside from an accumulation of our own notes and experiences as teachers, we recognize the influence of colleagues at Daytona Beach Community College as well as fellow presenters and attendees of national mathematics con- ferences and meetings. Perhaps our single greatest source of inspiration has been our students, who ask good, probing questions every day and challenge us to find new and better ways to convey mathematical concepts. We gratefully acknowl- edge the part that each has played in the writing of this book. In designing the framework for this text, the time we have spent with our students has proved especially valuable. Over the years we have observed that students struggle consistently with certain topics. We have also come to know the influence of forces beyond the math, particularly motivational issues. An awareness of the various pitfalls has enabled us to tailor pedagogy and tech- niques that directly address students’ needs and promote their success. These techniques and pedagogy are outlined here. Active Classroom First, we believe students retain more of what they learn when they are actively engaged in the classroom. Consequently, as we wrote each section of text, we also wrote accompanying worksheets called Classroom Activities to foster ac- countability and to encourage classroom participation. Classroom Activities re- semble the examples that students encounter in the textbook. The activities can be assigned to individual students or to pairs or groups of students. Most of the activities have been tested in the classroom with our own students. In one class in particular, the introduction of Classroom Activities transformed a group of “clock watchers” into students who literally had to be ushered out of the class- room so that the next class could come in. The activities can be found in the Instructor’s Resource Manual, which is available through MathZone. Conceptual Support While we believe students must practice basic skills to be successful in any math- ematics class, we also believe concepts are important. To this end, we have in- cluded numerous writing questions and homework exercises that ask students to “interpret the meaning in the context of the problem.” These questions make stu- dents stop and think, so they can process what they learn. In this way, students will learn underlying concepts. They will also form an understanding of what their answers mean in the contexts of the problems they solve. Writing Style Many students believe that reading a mathematics text is an exercise in futility. However, students who take the time to read the text and features may cast that notion aside. In particular, the Tips and Avoiding Mistakes boxes should prove xi
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page xii BA CONFIRMING PAGES xii Preface especially enlightening. They offer the types of insights and hints that are usually only revealed during classroom lecture. On the whole, students should be very comfortable with the reading level, as the language and tone are consistent with those used daily within our own developmental mathematics classes. Real-World Applications Another critical component of the text is the inclusion of contemporary real- world examples and applications. We based examples and applications on in- formation that students encounter daily when they turn on the news, read a magazine, or surf the Internet. We incorporated data for students to answer math- ematical questions based on information in tables and graphs. When students en- counter facts or information that is meaningful to them, they will relate better to the material and remember more of what they learn. Study Skills Many students in this course lack the basic study skills needed to be successful. Therefore, at the beginning of the homework exercises, we included a set of Study Skills Exercises. The exercises focus on one of nine areas: learning about the course, using the text, taking notes, completing homework assignments, test taking, time management, learning styles, preparing for a final exam, and defining key terms. Through completion of these exercises, students will be in a better posi- tion to pass the class and adopt techniques that will benefit them throughout their academic careers. Language of Mathematics Finally, for students to succeed in mathematics, they must be able to understand its language and notation. We place special emphasis on the skill of translating mathematical notation to English expressions and vice versa through Translat- ing Expressions Exercises. These appear intermittently throughout the text. We also include key terms in the homework exercises and ask students to define these terms. What Sets This Book Apart? We believe that the thoughtfully designed pedagogy and contents of this text- book offer any willing student the opportunity to achieve success, opening the door to a wider world of possibilities. While this textbook offers complete coverage of the beginning algebra cur- riculum, there are several concepts that receive special emphasis. Problem Recognition Problem recognition is an important theme carried throughout this edition and is integrated into the textbook in a number of different ways. First, we developed Problem Recognition Exercises that appear in selected chapters. The purpose of the Problem Recognition Exercises is to present a collection of problems that may look very similar to students, upon first glance, but are actually quite different in the manner of their individual solutions. By completing these exercises, students gain a greater awareness in problem recognition—that is, identifying a particular problem type upon inspection and applying the appropriate method to solve it.
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page xiii BA CONFIRMING PAGES Preface xiii We have carefully selected the content areas that seem to present the greatest challenge for students in terms of their ability to differentiate among various problem types. For these topics (listed below) we developed Problem Recognition Exercises. Addition and Subtraction of Signed Numbers (page 88) Properties of Exponents (page 404) Operations on Polynomials (page 434) Operations on Rational Expressions (page 552) Comparing Rational Equations and Rational Expressions (page 571) Operations on Radicals (page 650) The problem recognition theme is also threaded throughout the book within the exercise sets. In particular, Section 6.6, “General Factoring Summary,” is worth special mention. While not formally labeled “Problem Recognition,” each factor- ing exercise requires students to label the type of factoring problem presented before attempting to factor the polynomial (see page 493, directions for problems 7–74). The concept of problem recognition is also applied in every chapter, on a more micro level. We looked for opportunities within the section-ending Practice Ex- ercises to include exercises that involve comparison between problem types. See, for example, page 422, exercises 2–13 page 628, exercises 91 and 93 as well as 103 and 105 page 642, exercises 74–79 (contrast parts a and b) page 649, exercises 51–58 page 649, exercises 59–62 We also included Mixed Exercises that appear in many of the Practice Ex- ercise sets to give students opportunities to practice exercises that are not lumped together by problem type. We firmly believe that students who effectively learn how to distinguish between various problems and the methods to solve them will be better prepared for Intermediate Algebra and courses beyond. Design While the content of a textbook is obviously critical, we believe that the design of the page is equally vital. We have often heard instructors describe the impor- tance of “white space” in the design of developmental math textbooks and the need for simplicity, to prevent distractions. All of these comments have factored heavily in the page layout of this textbook. For example, we left ample space between exercises in the section-ending Practice Exercise sets to make it easier for students to read and complete homework assignments. Similarly, we developed design treatments within sections to present the content, including examples, definitions, and summary boxes, in an organized and reader-friendly way. We also limited the number of colors and photos in use, in an effort to avoid distraction on the pages. We believe these considerations di- rectly reflect the needs of our students and will enable them to navigate through the content successfully. Chapter R Chapter R is a reference chapter. We designed it to help students reacquaint them- selves with the fundamentals of fractions, decimals, percents, and geometry. This chapter also addresses study skills and helpful hints to use the resources provided in the text and its supplements.
• miL28711_fm_i-xxvi 11:16:2006 12:21 Page xv BA CONFIRMING PAGES Preface xv Acknowledgments and Reviewers The development of this textbook would never have been possible without the cre- ative ideas and constructive feedback offered by many reviewers. We are especially thankful to the following instructors for their valuable feedback and careful re- view of the manuscript. Board of Advisors Valarie Beaman-Hackle, Macon State College Michael Everett, Santa Ana College Teresa Hasenauer, Indian River Community College Lori Holdren, Manatee Community College–Bradenton Becky Hubiak, Tidewater Community College Barbara Hughes, San Jacinto College–Pasadena Mike Kirby, Tidewater Community College Manuscript Reviewers Cedric Atkins, Charles Stewart Mott Community College David Bell, Florida Community College Emilie Berglund, Utah Valley State College Kirby Bunas, Santa Rosa Junior College Annette Burden, Youngstown State University Susan Caldiero, Cosumnes River College Edie Carter, Amarillo College Marcial Echenique, Broward Community College Karen Estes, St. Petersburg College Renu Gupta, Louisiana State University–Alexandria Rodger Hergert, Rock Valley College Linda Ho, El Camino College Michelle Hollis, Bowling Green Community College Laura Hoye, Trident Technical College Randa Kress, Idaho State University–Pocatello Donna Krichiver, Johnson County Community College Karl Kruczek, Northeastern State University Kathryn Lavelle, Westchester Community College Jane Loftus, Utah Valley State College Gary McCracken, Shelton State Community College Karen Pagel, Dona Ana Branch Community College Peter Remus, Chicago State University Daniel Richbart, Erie Community College–City Campus Special thanks go to Doris McClellan-Lewis for preparing the Instructor’s Solutions Manual and the Student’s Solution Manual and to Lauri Semarne for her work ensuring accuracy. Many, many thanks to Yolanda Davis,Andrea Hendricks, Patricia Jayne, and Cynthia Cruz for their work in the video series and to Kelly Jackson, an awesome teacher, for preparing the Instructor Notes. To Pat Steele, we appre- ciate your watchful eye over our manuscript. Finally, we are forever grateful to the many people behind the scenes at McGraw-Hill, our publishing family. To Erin Brown, our lifeline on this project, without whom we’d be lost. To Liz Haefele for her passion for excellence and
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page xvi BA CONFIRMING PAGES xvi Preface constant inspiration. To David Millage and Barb Owca for their countless hours of support and creative ideas promoting all of our efforts. To Jeff Huettman and Amber Huebner for the awesome technology so critical to student success, and fi- nally to Vicki Krug for keeping the train on the track during production. Most importantly, we give special thanks to all the students and instructors who use Beginning Algebra second edition in their classes. Julie Miller Molly O’Neill Nancy Hyde
• miL28711_fm_i-xxvi 11:16:2006 12:21 Page xviii BA CONFIRMING PAGES Guided Tour Chapter Opener Each chapter opens with a puzzle relating to the content of the chapter. Section titles are clearly listed for easy reference. Linear Equations and Inequalities 2.1 Addition, Subtraction, Multiplication, and Division 2 Properties of Equality 2.2 Solving Linear Equations 2.3 Linear Equations: Clearing Fractions and Decimals 2.4 Applications of Linear Equations: Introduction to Problem Solving 2.5 Applications Involving Percents 2.6 Formulas and Applications of Geometry 2.7 Linear Inequalities In this chapter we learn how to solve linear equations and inequalities in one variable. This important category of equations and inequalities is used in a variety of applications. The list of words contains key terms used in this chapter. Search for them in the puzzle and in the text throughout the chapter. By the end of this chapter, you should be familiar with all of Z C these terms. E L Q A U M P R N I E L Key Terms C D K I W E O P N V M X C O N T R A D I C T I O N D compound identity notation L M S S O C L T K E T K O E conditional inequality percent I P L N N Y I I Z G U I I C consecutive integer property N O A O O T U D V E C N T I contradiction interest set-builder E U R I I I B N Y R E T A M decimal interval solution A N E T T T T O A Q S E U A equation linear R D T U A N E C U H N R Q L fractions literal N I L T E S A A N O E E B L O O D L Z Y R C S A N S N I L Q G E F T I N T E R V A L R Q Y T R E P O R P T N E C R E P A P L M Q 121 Section 3.1 Rectangular Coordinate System Concepts 1. Interpreting Graphs Concepts 1. Interpreting Graphs Mathematics is a powerful tool used by scientists and has directly contributed 2. Plotting Points in a to the highly technical world we live in. Applications of mathematics have led Rectangular Coordinate System to advances in the sciences, business, computer technology, and medicine. A list of important learning concepts is provided One fundamental application of mathematics is the graphical representation of 3. Applications of Plotting and Identifying Points numerical information (or data). For example, Table 3-1 represents the number of clients admitted to a drug and alcohol rehabilitation program over a 12-month at the beginning of each section. Each concept period. corresponds to a heading within the section and Table 3-1 Number of within the exercises, making it easy for students Month Clients Jan. 1 55 to locate topics as they study or as they work Feb. 2 62 March 3 64 through homework exercises. April 4 60 May 5 70 June 6 73 July 7 77 Aug. 8 80 Sept. 9 80 Oct. 10 74 Nov. 11 85 Dec. 12 90 In table form, the information is difficult to picture and interpret. It appears that on a monthly basis, the number of clients fluctuates. However, when the data are represented in a graph, an upward trend is clear (Figure 3-1). y Number of Clients Admitted to Program 100 Number of Clients 80 60 40 20 0 x 0 1 2 3 4 5 6 7 8 9 10 11 12 Month (x ϭ 1 corresponds to Jan.) Figure 3-1 xviii
• miL28711_fm_i-xxvi 10/10/06 12:54 AM Page xxi BA CONFIRMING PAGES Guided Tour xxi Icon Key The following key has been prepared for easy identification of “themed” exercises appearing within the Practice Exercises. 178 Chapter 2 Linear Equations and Inequalities Section 2.6 Practice Exercises Student Edition Boost your GRADE at • Practice Problems • Self-Tests • e-Professors • Videos mathzone.com! • NetTutor • Exercises Keyed to Video Study Skills Exercises 1. A good technique for studying for a test is to choose four problems from each section of the chapter and • Calculator Exercises write each of them along with the directions on a 3 ϫ 5 card. On the back, put the page number where you found that problem. Then shuffle the cards and test yourself on the procedure to solve each problem. If you find one that you do not know how to solve, look at the page number and do several of that type. Write four problems you would choose for this section. AIE only 2. Define the key term: literal equation • Writing Review Exercises For Exercises 3–7, solve the equation. • Translating Expressions 3. 312y ϩ 32 Ϫ 41Ϫy ϩ 12 ϭ 7y Ϫ 10 4. Ϫ13w ϩ 42 ϩ 51w Ϫ 22 Ϫ 316w Ϫ 82 ϭ 10 1x Ϫ 32 ϩ ϭ 3x Ϫ x ϩ ϭ 1x Ϫ 42 1 3 3 5 1 1 • Geometry 5. 2 4 4 6. 6 2 4 7. 0.51y ϩ 22 Ϫ 0.3 ϭ 0.4y ϩ 0.5 Study Skills Exercises appear at the beginning of Concept 1: Formulas For Exercises 8–39, solve for the indicated variable. selected exercise sets. They are designed to help 8. P ϭ a ϩ b ϩ c for a 9. P ϭ a ϩ b ϩ c for b 10. x ϭ y Ϫ z for y students learn vocabulary and techniques to 11. c ϩ d ϭ e for d 12. p ϭ 250 ϩ q for q 13. y ϭ 35 ϩ x for x improve their study habits including exam 14. d ϭ rt for t 15. d ϭ rt for r 16. PV ϭ nrt for t preparation, note taking, and time management. 17. P1V1 ϭ P2V2 for V1 18. x Ϫ y ϭ 5 for x 19. x ϩ y ϭ Ϫ2 for y 20. 3x ϩ y ϭ Ϫ19 for y 21. x Ϫ 6y ϭ Ϫ10 for x 22. 2x ϩ 3y ϭ 6 for y 23. 5x ϩ 2y ϭ 10 for y 24. Ϫ2x Ϫ y ϭ 9 for x 25. 3x Ϫ y ϭ Ϫ13 for x In the Practice Exercises, where appropriate, 26. 4x Ϫ 3y ϭ 12 for y 27. 6x Ϫ 3y ϭ 4 for y 28. ax ϩ by ϭ c for y students are asked to define the Key Terms that 29. ax ϩ by ϭ c for x 30. A ϭ P11 ϩ rt2 for t 31. P ϭ 21L ϩ w2 for L are presented in the section. Assigning these xϩy 32. a ϭ 21b ϩ c2 for c 33. 31x ϩ y2 ϭ z for x 34. Q ϭ for y exercises will help students to develop and 2 expand their mathematical vocabularies. 35. Q ϭ aϪb 2 for a 36. M ϭ a S for a 37. A ϭ 1 3 1a ϩ b ϩ c2 for c GMm 38. P ϭ I R for R 2 39. F ϭ for m Review Exercises also appear at the start of the d2 Practice Exercises. The purpose of the Review Exercises is to help students retain their knowledge of concepts previously learned. Section 1.3 Addition of Real Numbers 71 Writing Exercises offer students an 106. 5 1x 107. 19 ϩ x2 For Exercises 102–111, use the order of operations to evaluate the expression when x ϭ 4, y ϭ 2, and z ϭ 10. opportunity to conceptualize and communicate 102. 2y3 103. 3z2 104. 0 z Ϫ 8 0 105. 0 x Ϫ 3 0 108. yz Ϫ x 109. z Ϫ xy their understanding of algebra. These, along with 110. xy2 111. yx2 the Translating Expressions Exercises , For Exercises 112–123, translate each algebraic expression into an English phrase. (Answers may vary.) 112. 5 ϩ r 113. 18 Ϫ x 114. s Ϫ 14 115. y ϩ 12 enable students to strengthen their command of 120. 15 121. 110 116. xyz 117. 7x ϩ 1 118. 52 119. 63 mathematical language and notation and to 122. 73 123. 102 improve their reading and writing skills. 124. Some students use the following common memorization device (mnemonic) to help them remember the order of operations: the acronym PEMDAS or Please Excuse My Dear Aunt Sally to remember Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction. The problem with this mnemonic is that it suggests that multiplication is done before division and similarly, it suggests that addition is performed before subtraction. Explain why following this acronym may give incorrect answers for the expressions: a. 36 Ϭ 4 ؒ 3
• miL28711_fm_i-xxvi 10/5/06 01:03 AM Page xxiii BA CONFIRMING PAGES Guided Tour xxiii Chapter 6 SUMMARY Section 6.1 Greatest Common Factor and Factoring by Grouping Key Concepts Examples The greatest common factor (GCF) is the greatest Example 1 factor common to all terms of a polynomial. To factor 3x1a ϩ b2 Ϫ 51a ϩ b2 Greatest common factor is 1a ϩ b2. out the GCF from a polynomial, use the distributive property. A four-term polynomial may be factorable by ϭ 1a ϩ b213x Ϫ 52 grouping. Steps to Factoring by Grouping Example 2 1. Identify and factor out the GCF from all four 60xa Ϫ 30xb Ϫ 80ya ϩ 40yb ϭ 10 36xa Ϫ 3xb Ϫ 8ya ϩ 4yb4 terms. 2. Factor out the GCF from the first pair of terms. Factor out GCF. Factor out the GCF or its opposite from the ϭ 1033x12a Ϫ b2 Ϫ 4y12a Ϫ b2 4 Factor by second pair of terms. grouping. 3. If the two terms share a common binomial factor, factor out the binomial factor. ϭ 1012a Ϫ b213x Ϫ 4y2 Chapter 6 Review Exercises Section 6.1 26. When factoring a polynomial of the form ax2 Ϫ bx ϩ c, should the signs of the binomials For Exercises 1–4, identify the greatest common factor be both positive, both negative, or different? between each group of terms. 1. 15a2b4, 30a3b, 9a5b3 2. 31x ϩ 52, x1x ϩ 52 27. When factoring a polynomial of the form 3. 2c3 13c Ϫ 52, 4c13c Ϫ 52 4. Ϫ2wyz, Ϫ4xyz ax2 ϩ bx ϩ c, should the signs of the binomials be both positive, both negative, or different? End-of-Chapter Summary and Exercises 28. When factoring a polynomial of the form For Exercises 5–10, factor out the greatest common ax2 ϩ bx Ϫ c, should the signs of the binomials factor. 5. 6x2 ϩ 2x4 Ϫ 8x 6. 11w3y3 Ϫ 44w2y5 be both positive, both negative, or different? The Summary, located at the end of each 7. Ϫt2 ϩ 5t 8. Ϫ6u2 Ϫ u For Exercises 29–40, factor the trinomial using the trial-and-error method. chapter, outlines key concepts for each section 9. 3b1b ϩ 22 Ϫ 71b ϩ 22 29. 2y2 Ϫ 5y Ϫ 12 30. 4w2 Ϫ 5w Ϫ 6 and illustrates those concepts with examples. 10. 215x ϩ 92 ϩ 8x15x ϩ 92 31. 10z2 ϩ 29z ϩ 10 32. 8z2 ϩ 6z Ϫ 9 Following the Summary is a set of Review Exercises that are organized by section. A Chapter Test appears after each set of Review Chapter 6 Test Exercises. Chapters 2–9 also include Cumulative 1. Factor out the GCF: 15x4 Ϫ 3x ϩ 6x3 23. m2n2 Ϫ 81 24. 16a2 Ϫ 64b2 2. Factor by grouping: 7a Ϫ 35 Ϫ a2 ϩ 5a 25. 64x3 Ϫ 27y6 Reviews that follow the Chapter Tests. These end- 3. Factor the trinomial: 6w2 Ϫ 43w ϩ 7 For Exercises 26–30, solve the equation. of-chapter materials provide students with ample 4. Factor the difference of squares: 169 Ϫ p2 26. 12x Ϫ 321x ϩ 52 ϭ 0 27. x2 Ϫ 7x ϭ 0 opportunity to prepare for quizzes or exams. 5. Factor the perfect square trinomial: 28. x2 Ϫ 6x ϭ 16 29. x15x ϩ 42 ϭ 1 q 2 Ϫ 16q ϩ 64 30. y3 ϩ 10y2 Ϫ 9y Ϫ 90 ϭ 0 6. Factor the sum of cubes: 8 ϩ t 3 31. A tennis court has area of 312 yd2. If the length is 2 yd more than twice the width, find the For Exercises 7–25, factor completely. dimensions of the court. 7. a2 ϩ 12a ϩ 32 8. x2 ϩ x Ϫ 42 32. The product of two consecutive odd integers is 9. 2y2 Ϫ 17y ϩ 8 10. 6z2 ϩ 19z ϩ 8 35. Find the integers. 11. 9t 2 Ϫ 100 12. v2 Ϫ 81 33. The height of a triangle is 5 in. less than the length of the base. The area is 42 in2. Find the 13. 3a2 ϩ 27ab ϩ 54b2 14. c4 Ϫ 1 length of the base and the height of the triangle. 15. xy Ϫ 7x ϩ 3y Ϫ 21 16. 49 ϩ p2 34. The hypotenuse of a right triangle is 2 ft less 17. Ϫ10u2 ϩ 30u Ϫ 20 18. 12t 2 Ϫ 75 than three times the shorter leg. The longer leg is 3 ft less than three times the shorter leg. Find 19. 5y Ϫ 50y ϩ 125 2 20. 21q ϩ 14q 2 the length of the shorter leg. 21. 2x3 ϩ x2 Ϫ 8x Ϫ 4 22. y3 Ϫ 125 Chapters 1–6 Cumulative Review Exercises 282 ϩ 62 For Exercises 1–2, simplify completely. 8. Find an equation of the line passing through the 0 4 Ϫ 25 Ϭ 1Ϫ52 ؒ 2 0 point (Ϫ3, 5) and having a slope of 3. Write the 1. final answer in slope-intercept form. 9. Solve the system. 2x Ϫ 3y ϭ 4 2. Solve for t: 5 Ϫ 21t ϩ 42 ϭ 3t ϩ 12 5x Ϫ 6y ϭ 13 3. Solve for y: 3x Ϫ 2y ϭ 8 For Exercises 10–12, perform the indicated operations. 10. 2 a y3 Ϫ y2 Ϫ 7b Ϫ a y3 ϩ y2 ϩ 5yb 4. A child’s piggy bank has \$3.80 in quarters, 1 3 2 1 dimes, and nickels. The number of nickels is two 3 2 3 2 more than the number of quarters. The number of dimes is three less than the number of 11. 14p2 Ϫ 5p Ϫ 1212p Ϫ 32 quarters. Find the number of each type of coin in the bank. 12. 12w Ϫ 72 2 5. Solve the inequality. Graph the solution on a 13. Divide using long division: number line and write the solution set in interval 1r4 ϩ 2r3 Ϫ 5r ϩ 12 Ϭ 1r Ϫ 32 notation. 5 5 c12cϪ5 Ϫ xՅ 14. 12 3 c3
• miL28711_fm_i-xxvi 11/17/2006 23:16PM Page xxv BA CONFIRMING PAGES Supplements xxv search for questions by topic, format, or difficulty level; to edit existing questions or to add new ones; and to scramble questions and answer keys for multiple ver- sions of a single test. Hundreds of text-specific, open-ended, and multiple-choice questions are included in the question bank. Sample chapter tests are also provided. ALEKS (Assessment and LEarning in Knowledge Spaces) is an artificial-intelligence-based system for mathematics learning, available over the Web 24/7. Using unique adaptive questioning, ALEKS accurately assesses what topics each student knows and then determines exactly what each student is ready to learn next. ALEKS interacts with the students much as a skilled human tutor would, moving between explanation and practice as needed, correcting and ana- lyzing errors, defining terms and changing topics on request, and helping them master the course content more quickly and easily. Moreover, the new ALEKS 3.0 now links to text-specific videos, multimedia tutorials, and textbook pages in PDF format. ALEKS also offers a robust classroom management system that enables in- structors to monitor and direct student progress toward mastery of curricular goals. See www.highed.aleks.com. New Connect2Developmental Mathematics Video Series! Available on DVD and the MathZone website, these innovative videos bring essential Developmental Mathematics concepts to life! The videos take the con- cepts and place them in a real world setting so that students make the connec- tion from what they learn in the classroom to real world experiences outside the classroom. Making use of 3D animations and lectures, Connect2Developmental Mathematics video series answers the age-old questions “Why is this important” and “When will I ever use it?” The videos cover topics from Arithmetic and Basic Mathematics through the Algebra sequence, mixing student-oriented themes and settings with basic theory. Miller/O’Neill/Hyde Video Lectures on Digital Video Disk (DVD) In the videos, qualified instructors work through selected problems from the text- book, following the solution methodology employed in the text. The video series is available on DVD or online as an assignable element of MathZone. The DVDs are closed-captioned for the hearing-impaired, are subtitled in Spanish, and meet the Americans with Disabilities Act Standards for Accessible Design. Instructors may use them as resources in a learning center, for online courses, and/or to provide extra help for students who require extra practice. Annotated Instructor ’s Edition In the Annotated Instructor’s Edition (AIE), answers to all exercises and tests appear adjacent to each exercise, in a color used only for annotations. The AIE also contains Instructor Notes that appear in the margin. The notes may assist with lecture preparation. Also found in the AIE are icons within the Practice Ex- ercises that serve to guide instructors in their preparation of homework as- signments and lessons. Instructor ’s Solutions Manual The Instructor’s Solutions Manual provides comprehensive, worked-out solutions to all exercises in the Chapter Openers; Practice Exercises; the Problem Recog- nition Exercises; the end-of-chapter Review Exercises; the Chapter Tests; and the Cumulative Review Exercises.
• miL28711_fm_i-xxvi 12:12:06 10:07am Page xxvi BA CONFIRMING PAGES xxvi Supplements For the Student www.mathzone.com McGraw-Hill’s MathZone is a powerful Web-based tutorial for homework, quizzing, testing, and multimedia instruction. Also available in CD-ROM format, MathZone offers: Practice exercises based on the text and generated in an unlimited quantity for as much practice as needed to master any objective Video clips of classroom instructors showing how to solve exercises from the text, step by step e-Professor animations that take the student through step-by-step instruc- tions, delivered on-screen and narrated by a teacher on audio, for solving ex- ercises from the textbook; the user controls the pace of the explanations and can review as needed NetTutor, which offers personalized instruction by live tutors familiar with the textbook’s objectives and problem-solving methods. Every assignment, exercise, video lecture, and e-Professor is derived from the textbook. Student ’s Solutions Manual The Student’s Solutions Manual provides comprehensive, worked-out solutions to the odd-numbered exercises in the Practice Exercise sets; the Problem Recog- nition Exercises, the end-of-chapter Review Exercises, the Chapter Tests, and the Cumulative Review Exercises. Answers to the odd-and the even-numbered entries to the Chapter Opener puzzles are also provided. New Connect2Developmental Mathematics Video Series! Available on DVD and the MathZone website, these innovative videos bring essential Developmental Mathematics concepts to life! The videos take the concepts and place them in a real world setting so that students make the connection from what they learn in the classroom to real world experiences outside the classroom. Making use of 3D animations and lectures, Connect2Developmental Mathematics video series answers the age-old questions “Why is this important” and “When will I ever use it?” The videos cover topics from Arithmetic and Basic Mathematics through the Algebra sequence, mixing student-oriented themes and settings with basic theory. Video Lectures on Digital Video Disk The video series is based on exercises from the textbook. Each presenter works through selected problems, following the solution methodology employed in the text. The video series is available on DVD or online as part of MathZone. The DVDs are closed-captioned for the hearing impaired, are subtitled in Spanish, and meet the Americans with Disabilities Act Standards for Accessible Design. NetTutor Available through MathZone, NetTutor is a revolutionary system that enables students to interact with a live tutor over the Web. NetTutor’s Web-based, graph- ical chat capabilities enable students and tutors to use mathematical notation and even to draw graphs as they work through a problem together. Students can also submit questions and receive answers, browse previously answered questions, and view previous sessions. Tutors are familiar with the textbook’s objectives and problem-solving styles.
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 1 BA CONFIRMING PAGES Section 1 Section Title 1 Reference R R.1 Study Tips R.2 Fractions R.3 Decimals and Percents R.4 Introduction to Geometry Chapter R is a reference chapter that provides a review of the basic opera- tions on fractions, decimals, and percents. It also offers background on some of the important facts from geometry that will be used later in the text. As you work through Section R.4, see if you recognize any of these important shapes and figures. Match each figure number on the left with a letter on the right. Then fill in the blanks below with the appropriate letter. The letters will form a word to complete the puzzle. 1 6 n equilateral triangle s sphere i complementary angles 2 7 t right circular cylinder 3 s supplementary angles 8 p trapezoid 4 o parallelogram 9 l right triangle 5 e rectangle Without geometry, life would be 5 3 8 1 6 9 2 7 4 1
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 4 BA CONFIRMING PAGES 4 Chapter R Reference Time Mon. Tues. Wed. Thurs. Fri. Sat. Sun. 7–8 8–9 9–10 10–11 11–12 12–1 1–2 2–3 3–4 4–5 5–6 6–7 7–8 8–9 9–10 3. Taking 12 credit hours is the equivalent of a full-time job. Often students try to work too many hours while taking classes at school. a. Write down how many hours you work per week and the number of credit hours you are taking this term. number of hours worked per week _______________ number of credit hours this term _______________ b. The next table gives a recommended limit to the number of hours you should work for the number of credit hours you are taking at school. (Keep in mind that other responsibilities in your life such as your family might also make it necessary to limit your hours at work even more.) How do your numbers from part (a) compare to those in the table? Are you working too many hours? Number of Maximum number of credit hours hours of work per week 3 40 6 30 9 20 12 10 15 0 4. It is important to establish a place where you can study—someplace that has few distractions and is readily available. Answer the questions about the space that you have chosen. a. Is there enough room to spread out books and paper to do homework? b. Is this space available anytime? c. Are there any distractions? Can you be interrupted? d. Is the furniture appropriate for studying? That is, is there a comfortable chair and good lighting? 5. Organization is an important ingredient to success. A calendar or pocket planner is a valuable resource for keeping track of assignments and test dates. Write the date of the first test in this class.
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 7 BA CONFIRMING PAGES Section R.2 Fractions 7 A Fraction and Its Parts Fractions are numbers of the form b , where b ϭ a Ϭ b and b does not equal a a zero. a In the fraction b, the numerator is a, and the denominator is b. The denominator of a fraction indicates how many equal parts divide the whole. The numerator indicates how many parts are being represented. For instance, suppose Jack wants to plant carrots in 2 of a rectangular garden. He can divide the 5 garden into five equal parts and use two of the parts for carrots (Figure R-1). 5 equal parts 2 parts The shaded region represents 2 of the garden. 5 Figure R-1 Definition of a Proper Fraction, an Improper Fraction, and a Mixed Number 1. If the numerator of a fraction is less than the denominator, the fraction is a proper fraction. A proper fraction represents a quantity that is less than a whole unit. 2. If the numerator of a fraction is greater than or equal to the denomina- tor, then the fraction is an improper fraction. An improper fraction rep- resents a quantity greater than or equal to a whole unit. 3. A mixed number is a whole number added to a proper fraction. 3 1 Proper Fractions: 5 8 7 8 Improper Fractions: 5 8 Mixed Numbers: 11 5 23 8 2. Prime Factorization To perform operations on fractions it is important to understand the concept of a factor. For example, when the numbers 2 and 6 are multiplied, the result (called the product) is 12. 2 ϫ 6 ϭ 12 factors product
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 8 BA CONFIRMING PAGES 8 Chapter R Reference The numbers 2 and 6 are said to be factors of 12. (In this context, we refer only to natural number factors.) The number 12 is said to be factored when it is written as the product of two or more natural numbers. For example, 12 can be factored in several ways: 12 ϭ 1 ϫ 12 12 ϭ 2 ϫ 6 12 ϭ 3 ϫ 4 12 ϭ 2 ϫ 2 ϫ 3 A natural number greater than 1 that has only two factors, 1 and itself, is called a prime number. The first several prime numbers are 2, 3, 5, 7, 11, and 13. A natural number greater than 1 that is not prime is called a composite number. That is, a composite number has factors other than itself and 1. The first sev- eral composite numbers are 4, 6, 8, 9, 10, 12, 14, 15, and 16. The number 1 is neither prime nor composite. Example 1 Writing a Natural Number as a Product of Prime Factors Write each number as a product of prime factors. a. 12 b. 30 Solution: a. 12 ϭ 2 ϫ 2 ϫ 3 Divide 12 by prime numbers Or use a factor tree until only prime numbers are obtained. 12 2212 2 6 226 3 2 3 b. 30 ϭ 2 ϫ 3 ϫ 5 2230 30 3215 5 2 15 3 5 Skill Practice Write the number as a product of prime factors. 1. 40 2. 60 3. Simplifying Fractions to Lowest Terms The process of factoring numbers can be used to reduce or simplify fractions to lowest terms. A fractional portion of a whole can be represented by infinitely many fractions. For example, Figure R-2 shows that 1 is equivalent to 2, 3, 4, and so on. 2 4 6 8 1 2 3 4 2 4 6 8 Skill Practice Answers 1. 2 ϫ 2 ϫ 2 ϫ 5 Figure R-2 2. 2 ϫ 2 ϫ 3 ϫ 5
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 9 BA CONFIRMING PAGES Section R.2 Fractions 9 The fraction 1 is said to be in lowest terms because the numerator and denomi- 2 nator share no common factor other than 1. To simplify a fraction to lowest terms, we use the following important principle. The Fundamental Principle of Fractions a Consider the fraction and the nonzero number, c. Then, b a aϬc ϭ b bϬc The fundamental principle of fractions indicates that dividing both the numerator and denominator by the same nonzero number results in an equivalent fraction. For example, the numerator and denominator of the fraction 3 both share a com- 6 mon factor of 3. To reduce 3, we will divide both the numerator and denominator 6 by the common factor, 3. 3 3Ϭ3 1 ϭ ϭ 6 6Ϭ3 2 Before applying the fundamental principle of fractions, it is helpful to write the prime factorization of both the numerator and denominator. We can also use a slash, /, to denote division of common factors. Example 2 Simplifying a Fraction to Lowest Terms 30 Simplify the fraction to lowest terms. 12 Solution: From Example 1, we have 30 ϭ 2 ϫ 3 ϫ 5 and 12 ϭ 2 ϫ 2 ϫ 3. Hence, 30 2ϫ3ϫ5 ϭ Factor the numerator and denominator. 12 2ϫ2ϫ3 1 1 2ϫ3ϫ5 ϭ Divide the numerator and denominator by the 2ϫ2ϫ3 1 1 common factors, 2 and 3. Multiply 1 ϫ 1 ϫ 5 ϭ 5. 1 1 2ϫ3ϫ5 5 ϭ ϭ 2ϫ2ϫ3 2 1 1 Multiply 1 ϫ 2 ϫ 1 ϭ 2. Skill Practice Simplify to lowest terms. 20 3. 30 Skill Practice Answers 2 3. 3
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 10 BA CONFIRMING PAGES 10 Chapter R Reference Example 3 Simplifying a Fraction to Lowest Terms 14 Simplify to lowest terms. 42 Solution: 14 2ϫ7 ϭ Factor the numerator and denominator. 42 2ϫ3ϫ7 1 1 Multiply 1 ϫ 1 ϭ 1. Avoiding Mistakes: 2ϫ7 1 ϭ ϭ In Example 3, the common 2ϫ3ϫ7 3 factors 2 and 7 in the numerator 1 1 Multiply 1 ϫ 3 ϫ 1 ϭ 3. and denominator simplify to 1. It is important to remember to write Skill Practice Simplify to lowest terms. the factor of 1 in the numerator. The simplified form of the 32 4. fraction is 1 . 3 12 4. Multiplying Fractions Multiplying Fractions If b is not zero and d is not zero, then a c aϫc ϫ ϭ b d bϫd To multiply fractions, multiply the numerators and multiply the denominators. Example 4 Multiplying Fractions 1 1 Multiply the fractions: ϫ 4 2 Solution: 1 1 1ϫ1 1 ϫ ϭ ϭ Multiply the numerators. Multiply the 4 2 4ϫ2 8 denominators. Notice that the product 1 ϫ 1 represents a quantity that is 1 of 2 . Taking 4 of a quan- 4 2 4 1 1 tity is equivalent to dividing the quantity by 4. One-half of a pie divided into four pieces leaves pieces that each represent 1 of the pie (Figure R-3). 8 1 1 2 2 Skill Practice Answers 1 1 1 4 of 2 ϭ 8 8 4. 3 Figure R-3
• miL28711_ch00_001-048 9/20/06 09:07 AM Page 11 BA CONFIRMING PAGES Section R.2 Fractions 11 Skill Practice Multiply. 2 3 5. ϫ 7 4 Example 5 Multiplying Fractions Multiply the fractions. 7 15 2 13 1 a. ϫ b. ϫ c. 5 ϫ 10 14 13 2 5 Solution: 7 15 7 ϫ 15 a. ϫ ϭ Multiply the numerators, and 10 14 10 ϫ 14 multiply the denominators. Divide common factors in the numerator and denominator. 1 1 Multiply 1 ϫ 3 ϫ 1 ϭ 3. 7ϫ3ϫ5 3 ϭ ϭ 2ϫ5ϫ2ϫ7 4 1 1 Multiply 2 ϫ 1 ϫ 2 ϫ 1 ϭ 4. 1 1 Multiply 1 ϫ 1 ϭ 1. 2 13 2 ϫ 13 2 ϫ 13 1 b. ϫ ϭ ϭ ϭ ϭ1 13 2 13 ϫ 2 13 ϫ 2 1 1 1 Multiply 1 ϫ 1 ϭ 1. 1 5 1 c. 5 ϫ ϭ ϫ The whole number 5 can be 5 1 5 written as 5. 1 1 5ϫ1 1 ϭ ϭ ϭ1 Multiply and simplify to lowest 1ϫ5 1 1 terms. Skill Practice Multiply. 8 3 4 5 1 6. ϫ 7. ϫ 8. 10 ϫ 9 4 5 4 10 5. Dividing Fractions Before we divide fractions, we need to know how to find the reciprocal of a fraction. Notice from Example 5 that 13 ϫ 13 ϭ 1 and 5 ϫ 1 ϭ 1. The numbers 13 2 2 5 2 13 and 2 are said to be reciprocals because their product is 1. Likewise the num- bers 5 and 1 are reciprocals. 5 Skill Practice Answers 3 2 5. 6. 7. 1 8. 1 14 3
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 12 BA CONFIRMING PAGES 12 Chapter R Reference The Reciprocal of a Number Two nonzero numbers are reciprocals of each other if their product is 1. Therefore, the reciprocal of the fraction a b a b is because ϫ ϭ1 b a b a Number Reciprocal Product 2 13 2 13 ϫ ϭ1 13 2 13 2 1 8 1 (or equivalently 8) ϫ8ϭ1 8 1 8 6 aor equivalently b 6 1 1 6ϫ ϭ1 1 6 6 To understand the concept of dividing fractions, consider a pie that is half- eaten. Suppose the remaining half must be divided among three people, that is, 2 Ϭ 3. However, dividing by 3 is equivalent to taking 3 of the remaining 2 of the 1 1 1 pie (Figure R-4). 1 1 1 1 1 2 Ϭ3ϭ ؒ ϭ 2 2 3 6 1 1 2Ϭ3ϭ6 Figure R-4 This example illustrates that dividing two numbers is equivalent to multiplying the first number by the reciprocal of the second number. Division of Fractions Let a, b, c, and d be numbers such that b, c, and d are not zero. Then, multiply a c a d Ϭ ϭ ϫ b d b c reciprocal To divide fractions, multiply the first fraction by the reciprocal of the sec- ond fraction.
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 13 BA CONFIRMING PAGES Section R.2 Fractions 13 Example 6 Dividing Fractions Divide the fractions. 8 3 12 a. Ϭ b. Ϭ6 5 10 13 Solution: 8 3 8 10 a. Ϭ ϭ ϫ Multiply by the reciprocal of 10, which is 10. 3 3 5 10 5 3 2 8 ϫ 10 16 ϭ ϭ Multiply and simplify to lowest terms. 5ϫ3 3 1 12 12 6 b. Ϭ6ϭ Ϭ Write the whole number 6 as 6. 1 13 13 1 12 1 ϭ ϫ Multiply by the reciprocal of 6 , which is 1. 1 6 13 6 2 12 ϫ 1 2 ϭ ϭ Multiply and simplify to lowest terms. 13 ϫ 6 13 1 Skill Practice Divide. 12 8 9 9. Ϭ 10. Ϭ3 25 15 11 6. Adding and Subtracting Fractions Adding and Subtracting Fractions Two fractions can be added or subtracted if they have a common denomi- nator. Let a, b, and c, be numbers such that b does not equal zero. Then, a c aϩc a c aϪc ϩ ϭ and Ϫ ϭ b b b b b b To add or subtract fractions with the same denominator, add or subtract the numerators and write the result over the common denominator. Example 7 Adding and Subtracting Fractions with the Same Denominator Add or subtract as indicated. 1 7 13 3 a. ϩ b. Ϫ 12 12 5 5 Skill Practice Answers 9 3 9. 10. 10 11
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 14 BA CONFIRMING PAGES 14 Chapter R Reference Solution: TIP: The sum ϩ 12 1 12 7 1 7 1ϩ7 can be visualized as the a. ϩ ϭ Add the numerators. 12 12 12 sum of the pink and blue sections of the figure. 8 ϭ 12 2 ϭ Simplify to lowest terms. 3 13 3 13 Ϫ 3 b. Ϫ ϭ Subtract the numerators. 5 5 5 10 ϭ Simplify. 5 ϭ2 Simplify to lowest terms. Skill Practice Add or subtract as indicated. 2 5 5 1 11. ϩ 12. Ϫ 3 3 8 8 In Example 7, we added and subtracted fractions with the same denominators. To add or subtract fractions with different denominators, we must first become familiar with the idea of a least common multiple between two or more numbers. The least common multiple (LCM) of two numbers is the smallest whole num- ber that is a multiple of each number. For example, the LCM of 6 and 9 is 18. multiples of 6: 6, 12, 18, 24, 30, 36, . . . multiples of 9: 9, 18, 27, 36, 45, 54, . . . Listing the multiples of two or more given numbers can be a cumbersome way to find the LCM. Therefore, we offer the following method to find the LCM of two numbers. Steps to Finding the LCM of Two Numbers 1. Write each number as a product of prime factors. 2. The LCM is the product of unique prime factors from both numbers. If a factor is repeated within the factorization of either number, use that factor the maximum number of times it appears in either factorization. Example 8 Finding the LCM of Two Numbers Find the LCM of 9 and 15. Solution: 9ϭ3ϫ3 and 15 ϭ 3 ϫ 5 Factor the numbers. LCM ϭ 3 ϫ 3 ϫ 5 ϭ 45 The LCM is the product of the factors of 3 and 5, where 3 is repeated twice. Skill Practice Answers Skill Practice Find the LCM. 7 1 13. 10 and 25 11. 12. 13. 50 3 2
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 15 BA CONFIRMING PAGES Section R.2 Fractions 15 To add or subtract fractions with different denominators, we must first write each fraction as an equivalent fraction with a common denominator. A common denominator may be any common multiple of the denominators. However, we will use the least common denominator. The least common denominator (LCD) of two or more fractions is the LCM of the denominators of the fractions. The following steps outline the procedure to write a fraction as an equivalent fraction with a common denominator. Writing Equivalent Fractions To write a fraction as an equivalent fraction with a common denominator, multiply the numerator and denominator by the factors from the common denominator that are missing from the denominator of the original fraction. Note: Multiplying the numerator and denominator by the same nonzero quantity will not change the value of the fraction. Example 9 Writing Equivalent Fractions 1 1 a. Write the fractions 9 and 15 as equivalent fractions with the LCD as the denominator. b. Subtract 1 Ϫ 15. 9 1 Solution: From Example 8, we know that the LCM for 9 and 15 is 45. Therefore, the LCD of 1 and 15 is 45. 9 1 1 1ϫ5 5 Multiply numerator and denominator by 5. This a. ϭ ϭ 9 9ϫ5 45 creates a denominator of 45. 1 1ϫ3 3 Multiply numerator and denominator by 3. This ϭ ϭ 15 15 ϫ 3 45 creates a denominator of 45. 1 1 b. Ϫ 9 15 5 3 1 Write 1 and 15 as equivalent fractions with the same ϭ Ϫ 9 45 45 denominator. 2 ϭ Subtract. 45 Skill Practice 5 5 14. Write the fractions 8 and 12 as equivalent fractions with the LCD as the denominator. Example 10 Adding Fractions with Different Denominators Suppose Nakeysha ate 1 of an ice-cream pie, and her friend Carla ate 2 1 3 of the pie. How much of the ice-cream pie was eaten? Skill Practice Answers 15 10 14. , 24 24
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 16 BA CONFIRMING PAGES 16 Chapter R Reference Solution: 1 1 ϩ The LCD is 3 ϫ 2 ϭ 6. 2 3 1ϫ3 1ϫ2 Multiply numerator and denominator by the ϭ ϩ 2ϫ3 3ϫ2 missing factors. 3 2 ϭ ϩ 6 6 5 ϭ Add the fractions. 6 Together, Nakeysha and Carla ate 5 of the ice-cream pie. 6 By converting the fractions 2 and 1 to the same denominator, we are able 1 3 to add like-size pieces of pie (Figure R-5). Nakeysha ate 1 2 1 3 Carla ate 1 3 2ϭ6 1 2 3ϭ6 Figure R-5 Skill Practice 15. Adam painted 1 of a fence and Megan painted 4 1 6 of the fence. How much of the fence was painted? Example 11 Adding and Subtracting Fractions 1 5 11 Simplify: ϩ Ϫ . 2 8 16 Solution: Factor the denominators: 2 ϭ 2, 1 5 11 ϩ Ϫ 8 ϭ 2 ϫ 2 ϫ 2, and 2 8 16 16 ϭ 2 ϫ 2 ϫ 2 ϫ 2. The LCD is 2 ϫ 2 ϫ 2 ϫ 2 ϭ 16. Next write the fractions as equivalent fractions with the LCD. Multiply numerators and 1ϫ2ϫ2ϫ2 5ϫ2 11 ϭ ϩ Ϫ denominators by the factors 2ϫ2ϫ2ϫ2 8ϫ2 16 missing from each denominator. 8 10 11 ϭ ϩ Ϫ 16 16 16 8 ϩ 10 Ϫ 11 ϭ Add and subtract the numerators. 16 Skill Practice Answers 7 15. Together, Adam and Megan painted 5 ϭ Simplify. 12 of the fence. 16
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 17 BA CONFIRMING PAGES Section R.2 Fractions 17 Skill Practice Add. 2 1 5 16. ϩ ϩ 3 2 6 7. Operations on Mixed Numbers Recall that a mixed number is a whole number added to a fraction. The number 3 1 represents the sum of three wholes plus a half, that is, 3 1 ϭ 3 ϩ 1. For this 2 2 2 reason, any mixed number can be converted to an improper fraction by using addition. 1 1 6 1 7 3 ϭ3ϩ ϭ ϩ ϭ 2 2 2 2 2 TIP: A shortcut to writing a mixed number as an improper fraction is to multiply the whole number by the denominator of the fraction. Then add this value to the numerator of the fraction, and write the result over the denominator. 31 2 Multiply the whole number by the denominator: 3 ϫ 2 ϭ 6. Add the numerator: 6 ϩ 1 ϭ 7. Write the result over the denominator: 7. 2 To add, subtract, multiply, or divide mixed numbers, we will first write the mixed number as an improper fraction. Example 12 Operations on Mixed Numbers Perform the indicated operations. 1 1 1 a. 5 Ϫ2 b. 7 Ϭ3 3 4 2 Solution: 1 1 a. 5 Ϫ 2 3 4 16 9 ϭ Ϫ Write the mixed numbers as improper fractions. 3 4 16 ϫ 4 9ϫ3 The LCD is 12. Multiply numerators and ϭ Ϫ 3ϫ4 4ϫ3 denominators by the missing factors from the denominators. 64 27 ϭ Ϫ 12 12 37 1 ϭ or 3 Subtract the fractions. 12 12 Skill Practice Answers 16. 2
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 18 BA CONFIRMING PAGES 18 Chapter R Reference TIP: An improper fraction can also be written as a mixed number. Both answers are acceptable. Note that 37 36 1 1 1 ϭ ϩ ϭ3ϩ , or 3 12 12 12 12 12 This can easily be found by dividing. quotient remainder 3 37 1 12 ͤ 37 3 12 Ϫ36 12 1 divisor 1 b. 7 Ϭ3 Avoiding Mistakes: 2 Remember that when dividing (or 15 3 multiplying) fractions, a common ϭ Ϭ Write the mixed number and whole number as fractions. 2 1 denominator is not necessary. 5 15 1 ϭ ϫ Multiply by the reciprocal of 3, which is 1 . 1 3 2 3 1 5 1 ϭ or 2 The answer may be written as an improper fraction or as 2 2 a mixed number. Skill Practice Perform the indicated operations. Skill Practice Answers 3 1 2 5 17 5 22 17. 2 Ϫ 1 18. 3 Ϭ 5 17. or 1 18. 4 3 3 6 12 12 35 Section R.2 Practice Exercises Boost your GRADE at • Practice Problems • e-Professors mathzone.com! • Self-Tests • Videos • NetTutor Concept 1: Basic Definitions For Exercises 1–8, identify the numerator and denominator of the fraction. Then determine if the fraction is a proper fraction or an improper fraction. 7 2 9 5 1. 2. 3. 4. 8 3 5 2 6 4 12 5 5. 6. 7. 8. 6 4 1 1 For Exercises 9–16, write a proper or improper fraction associated with the shaded region of each figure. 9. 10.
• miL28711_ch00_001-048 9/20/06 09:14 AM Page 19 BA CONFIRMING PAGES Section R.2 Fractions 19 11. 12. 13. 14. 15. 16. For Exercises 17–20, write both an improper fraction and a mixed number associated with the shaded region of each figure. 17. 18. 19. 20. 21. Explain the difference between the set of whole numbers and the set of natural numbers. 22. Explain the difference between a proper fraction and an improper fraction. 23. Write a fraction that simplifies to 1 . (Answers may vary.) 2 24. Write a fraction that simplifies to 1 . (Answers may vary.) 3 Concept 2: Prime Factorization For Exercises 25–32, identify the number as either a prime number or a composite number. 25. 5 26. 9 27. 4 28. 2 29. 39 30. 23 31. 53 32. 51 For Exercises 33–40, write the number as a product of prime factors. 33. 36 34. 70 35. 42 36. 35 37. 110 38. 136 39. 135 40. 105 Concept 3: Simplifying Fractions to Lowest Terms For Exercises 41–52, simplify each fraction to lowest terms. 3 8 6 12 41. 42. 43. 44. 15 12 16 20
• miL28711_ch00_001-048 9/20/06 06:51 AM Page 20 BA CONFIRMING PAGES 20 Chapter R Reference 42 35 48 32 45. 46. 47. 48. 48 80 64 48 110 70 150 119 49. 50. 51. 52. 176 120 200 210 Concepts 4–5: Multiplying and Dividing Fractions For Exercises 53–54, determine if the statement is true or false. If it is false, rewrite as a true statement. 53. When multiplying or dividing fractions, it is necessary to have a common denominator. 54. When dividing two fractions, it is necessary to multiply the first fraction by the reciprocal of the second fraction. For Exercises 55–66, multiply or divide as indicated. 10 26 15 7 3 9 7 1 55. ϫ 56. ϫ 57. Ϭ 58. Ϭ 13 15 28 9 7 14 25 5 9 3 12 20 59. ϫ5 60. ϫ 14 61. Ϭ4 62. Ϭ5 10 7 5 6 5 10 7 55 18 24 9 13 1000 10 63. ϫ ϫ 64. ϫ ϫ 65. Ϭ 66. Ϭ 2 21 5 9 32 11 100 1000 17 3 1 67. Stephen’s take-home pay is \$1200 a month. If his rent is 4 of his pay, how much is his rent? 1 68. Gus decides to save 3 of his pay each month. If his monthly pay is \$2112, how much will he save each month? 69. On a college basketball team, one-third of the team graduated with honors. If the team has 12 members, how many graduated with honors? 3 70. Shontell had only enough paper to print out 5 of her book report before school. If the report is 10 pages long, how many pages did she print out? 1 71. Natalie has 4 yd of material with which she can make holiday aprons. If it takes 2 yd of material per apron, how many aprons can she make? 1 72. There are 4 cups of oatmeal in a box. If each serving is 3 of a cup, how many servings are contained in the box? 73. Gail buys 6 lb of mixed nuts to be divided into decorative jars that will each hold 3 4 lb of nuts. How many jars will she be able to fill? 74. Troy has a 7 in. nail that he must hammer into a board. Each strike of the hammer 8 1 moves the nail 16 in. into the board. How many strikes of the hammer must he make to drive the nail completely into the board? Concept 6: Adding and Subtracting Fractions For Exercises 75–78, add or subtract as indicated. 5 1 9 1 17 5 11 5 75. ϩ 76. ϩ 77. Ϫ 78. Ϫ 14 14 5 5 24 24 18 18
• miL28711_ch00_001-048 9/20/06 09:08 AM Page 21 BA CONFIRMING PAGES Section R.2 Fractions 21 For Exercises 79–84, find the least common denominator for each pair of fractions. 1 5 1 11 9 3 13 7 79. , 80. , 81. , 82. , 6 24 12 30 20 8 24 40 7 11 1 1 83. , 84. , 10 45 20 30 For Exercises 85–100, add or subtract as indicated. 1 3 3 1 3 3 12 1 85. ϩ 86. ϩ 87. Ϫ 88. Ϫ 8 4 16 2 8 10 35 10 7 2 11 5 7 5 3 9 89. Ϫ 90. Ϫ 91. ϩ 92. ϩ 26 13 24 16 18 12 16 20 3 1 1 1 5 5 3 8 93. Ϫ 94. Ϫ 95. ϩ 96. ϩ 4 20 6 24 12 16 25 35 1 3 5 1 2 5 4 1 3 9 4 3 97. ϩ ϩ 98. ϩ ϩ 99. ϩ ϩ 100. ϩ ϩ 6 4 8 2 3 12 7 2 4 10 5 4 Concept 7: Operations on Mixed Numbers For Exercises 101–123, perform the indicated operations. 3 1 4 7 1 7 101. 4 Ϭ 102. 2 Ϭ 103. 3 ϫ 5 10 5 11 5 8 1 4 2 2 2 104. 2 ϫ 105. 1 Ϭ 6 106. 2 Ϭ 2 5 9 5 7 107. A board 26 3 in. long must be cut into three pieces of equal length. Find 8 the length of each piece. 3 26 8 in. 108. 21 ϩ 13 8 8 109. 114 ϩ 114 3 1 110. 15 Ϫ 7 6 8 111. 21 Ϫ 5 3 6 7 3 112. 11 ϩ 33 6 4 113. 41 ϩ 22 2 3 114. 1 Ϫ 115. 2 Ϫ 8 7 116. A futon, when set up as a sofa, measures 35 ft wide. When it is opened to 6 be used as a bed, the width is increased by 13 ft. What is the total width of 4 this bed? x 117. A plane trip from Orlando to Detroit takes 23 hr. If the plane traveled for 4 5 3 6 ft 11 hr, how much time remains for the flight? 6 1 118. Antonio bought 2 lb of turkey, 1 lb of ham, and 3 3 4 lb of roast beef. How much meat did Antonio buy? 119. José ordered two seafood platters for a party. One platter has 11 lb of shrimp, and the other has 2 3 4 lb of shrimp. How many pounds does he have altogether?
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 22 BA CONFIRMING PAGES 22 Chapter R Reference 120. Ayako took a trip to the store 51 miles away. If she rode the bus for 45 miles and walked the rest of the way, 2 6 how far did she have to walk? 121. Average rainfall in Tampa, FL, for the month of November is 23 in. One stormy weekend 31 in. of rain fell. 4 8 How many inches of rain over the monthly average is this? 122. Maria has 4 yd of material. If she sews a dress that requires 31 yd, how much material will she have left? 8 123. Pete started working out at the gym several months ago. His waist measured 381 in. when he began and is 2 now 333 in. How many inches did he lose around his waist? 4 Section R.3 Decimals and Percents Concepts 1. Introduction to a Place Value System 1. Introduction to a Place Value In a place value number system, each digit in a numeral has a particular value System determined by its location in the numeral (Figure R-6). 2. Converting Fractions to Decimals Decimal Point 3. Converting Decimals to Fractions , , . on m te te th te 4. Converting Percents to th te hu hu hu ill n- nt ns ou n- ou es nd nd nd io th hs th sa Decimals and Fractions sa re re ns re ou ou nd nd ds dt d- sa sa s th hs th 5. Converting Decimals and nd nd s ou s th sa Fractions to Percents s nd s 6. Applications of Percents Figure R-6 For example, the number 197.215 represents 11 ϫ 1002 ϩ 19 ϫ 102 ϩ 17 ϫ 12 ϩ a2 ϫ b ϩ a1 ϫ b ϩ a5 ϫ b 1 1 1 10 100 1000 1 1 1 Each of the digits 1, 9, 7, 2, 1, and 5 is multiplied by 100, 10, 1, 10, 100, and 1000, respectively, depending on its location in the numeral 197.215. By obtaining a common denominator and adding fractions, we have 200 10 5 197.215 ϭ 100 ϩ 90 ϩ 7 ϩ ϩ ϩ 1000 1000 1000 215 215 ϭ 197 ϩ or 197 1000 1000 215 Because 197.215 is equal to the mixed number 197 1000, we read 197.215 as one hundred ninety-seven and two hundred fifteen thousandths. The decimal point is read as the word and. If there are no digits to the right of the decimal point, we usually omit the decimal point.
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 23 BA CONFIRMING PAGES Section R.3 Decimals and Percents 23 2. Converting Fractions to Decimals In Section R.2, we learned that a fraction represents part of a whole unit. Like- wise, the digits to the right of the decimal point represent a fraction of a whole unit. In this section, we will learn how to convert a fraction to a decimal number and vice versa. Converting a Fraction to a Decimal To convert a fraction to a decimal, divide the numerator of the fraction by the denominator of the fraction. Example 1 Converting Fractions to Decimals Convert each fraction to a decimal. 7 2 13 a. b. c. 40 3 7 Solution: 7 0.175 a. ϭ 0.175 40 40ͤ 7.000 The number 0.175 is 40 said to be a terminating 300 decimal because there 280 are no nonzero digits 200 to the right of the last 200 digit, 5. 0 2 0.666 . . . b. ϭ 0.666 . . . 3 3ͤ2.00000 The pattern 0.666 . . . 18 continues indefinitely. 20 Therefore, we say that 18 this is a repeating 20 decimal. 18 2... For a repeating decimal, a horizontal bar is often used to denote the repeating pattern after the decimal point. Hence, 2 ϭ 0.6. 3 13 1.857142857142 . . . c. ϭ 1.857142857142 . . . 7 7ͤ 13.0000000000000 The number 1.857142857142 . . . is also a repeating pattern, and in this case the pattern includes several digits. Therefore, we write 13 ϭ 1.857142. 7 Skill Practice Convert to a decimal. 5 1 15 1. 2. 3. 8 6 11 Skill Practice Answers 1. 0.625 2. 0.16 3. 1.36
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 24 BA CONFIRMING PAGES 24 Chapter R Reference 3. Converting Decimals to Fractions To convert a terminating decimal to a fraction, use the word name to write the number as a fraction or mixed number. Example 2 Converting Terminating Decimals to Fractions Convert each decimal to a fraction. a. 0.0023 b. 50.06 Solution: a. 0.0023 is read as twenty-three ten-thousandths. Thus, 23 0.0023 ϭ 10,000 b. 50.06 is read as fifty and six hundredths. Thus, 6 50.06 ϭ 50 100 3 ϭ 50 Simplify the fraction to lowest terms. 50 2503 ϭ Write the mixed number as a fraction. 50 Skill Practice Convert to a fraction. 4. 0.107 5. 11.25 Repeating decimals also can be written as fractions. However, the procedure to convert a repeating decimal to a fraction requires some knowledge of alge- bra. Table R-1 shows some common repeating decimals and an equivalent frac- tion for each. Table R-1 1 4 7 0.1 ϭ 0.4 ϭ 0.7 ϭ 9 9 9 2 5 8 0.2 ϭ 0.5 ϭ 0.8 ϭ 9 9 9 3 1 6 2 9 0.3 ϭ ϭ 0.6 ϭ ϭ 0.9 ϭ ϭ1 9 3 9 3 9 4. Converting Percents to Decimals and Fractions The concept of percent (%) is widely used in a variety of mathematical applications. The word percent means “per 100.” Therefore, we can write percents as fractions. 6 6% ϭ A sales tax of 6% means that 6 cents in tax is charged for 100 every 100 cents spent. Skill Practice Answers 91 91% ϭ The fact that 91% of the population is right-handed means 107 45 100 4. 5. that 91 people out of 100 are right-handed. 1000 4
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 25 BA CONFIRMING PAGES Section R.3 Decimals and Percents 25 91 1 The quantity 91% ϭ can be written as 91 ϫ or as 91 ϫ 0.01. 100 100 Notice that the % symbol implies “division by 100” or, equivalently, “multiplica- 1 tion by 100.” Thus, we have the following rule to convert a percent to a fraction (or to a decimal). Converting a Percent to a Decimal or Fraction 1 Replace the % symbol by Ϭ 100 (or equivalently ϫ or ϫ 0.01). 100 Example 3 Converting Percents to Decimals TIP: Multiplying by Convert the percents to decimals. 0.01 is equivalent to dividing by 100. This has a. 78% b. 412% c. 0.045% the effect of moving the decimal point two places Solution: to the left. a. 78% ϭ 78 ϫ 0.01 ϭ 0.78 b. 412% ϭ 412 ϫ 0.01 ϭ 4.12 c. 0.045% ϭ 0.045 ϫ 0.01 ϭ 0.00045 Skill Practice Convert the percent to a decimal. 6. 29% 7. 3.5% 8. 100% Example 4 Converting Percents to Fractions Convert the percents to fractions. 1 a. 52% b. 33 % c. 6.5% 3 Solution: 1 a. 52% ϭ 52 ϫ Replace the % symbol by 1 100 . 100 52 ϭ Multiply. 100 13 ϭ Simplify to lowest terms. 25 1 b. 33 1 % ϭ 33 1 ϫ 3 3 Replace the % symbol by 1 100 . 100 100 1 ϭ ϫ Write the mixed number as a fraction 33 1 ϭ 100. 3 3 3 100 100 ϭ Multiply the fractions. 300 1 Skill Practice Answers ϭ Simplify to lowest terms. 3 6. 0.29 7. 0.035 8. 1.00
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 26 BA CONFIRMING PAGES 26 Chapter R Reference 1 c. 6.5% ϭ 6.5 ϫ Replace the % symbol by 1 100 . 100 65 1 ϭ ϫ Write 6.5 as an improper fraction. 10 100 65 ϭ Multiply the fractions. 1000 13 ϭ Simplify to lowest terms. 200 Skill Practice Convert the percent to a fraction. 1 9. 30% 10. 120 % 11. 25% 2 5. Converting Decimals and Fractions to Percents To convert a percent to a decimal or fraction, we replace the % symbol by Ϭ 100. To convert a decimal or percent to a fraction, we reverse this process. Converting Fractions and Decimals to Percents Multiply the fraction or decimal by 100%. Example 5 Converting Decimals to Percents Convert the decimals to percents. a. 0.92 b. 10.80 c. 0.005 Solution: a. 0.92 ϭ 0.92 ϫ 100% ϭ 92% Multiply by 100%. b. 10.80 ϭ 10.80 ϫ 100% ϭ 1080% Multiply by 100%. c. 0.005 ϭ 0.005 ϫ 100% ϭ 0.5% Multiply by 100%. Skill Practice Convert the decimal to a percent. 12. 0.56 13. 4.36 14. 0.002 Example 6 Converting Fractions to Percents Convert the fractions to percents. 2 1 5 a. b. c. 5 16 3 Skill Practice Answers 3 241 1 9. 10. 11. 10 200 4 12. 56% 13. 436% 14. 0.2%
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 27 BA CONFIRMING PAGES Section R.3 Decimals and Percents 27 Solution: 2 2 a. ϭ ϫ 100% Multiply by 100%. 5 5 2 100 ϭ ϫ % Write the whole number as a fraction. 5 1 20 2 100 ϭ ϫ % Multiply fractions. 5 1 1 40 ϭ % or 40% Simplify. 1 1 1 b. ϭ ϫ 100% Multiply by 100%. 16 16 1 100 ϭ ϫ % Write the whole number as a fraction. 16 1 25 1 100 ϭ ϫ % Multiply the fractions. 16 1 4 25 ϭ % Simplify. 4 25 ϭ % or 6.25% The value 25 can be written in decimal form by 4 4 dividing 25 by 4. 5 5 c. ϭ ϫ 100% Multiply by 100%. 3 3 5 100 ϭ ϫ % Write the whole number as a fraction. 3 1 500 ϭ % Multiply fractions. 3 500 ϭ % or 166.6% The value 500 can be written in decimal form by 3 3 dividing 500 by 3. Skill Practice Convert the fraction to a percent. 7 9 1 15. 16. 17. 8 5 9 6. Applications of Percents Many applications involving percents involve finding a percent of some base number. For example, suppose a textbook is discounted 25%. If the book originally cost \$60, find the amount of the discount. In this example, we must find 25% of \$60. In this context, the word of means multiply. 25% of \$60 Skill Practice Answers 0.25 ϫ 60 ϭ 15 The amount of the discount is \$15. 15. 87.5% 16. 180% 1 17. 11.1% or 11 % Note that the decimal form of a percent is always used in calculations. Therefore, 9 25% was converted to 0.25 before multiplying by \$60.
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 28 BA CONFIRMING PAGES 28 Chapter R Reference Example 7 Applying Percentages Shauna received a raise, so now her new salary is 105% of her old salary. Find Shauna’s new salary if her old salary was \$36,000 per year. Solution: The new salary is 105% of \$36,000. 1.05 ϫ 36,000 ϭ 37,800 The new salary is \$37,800 per year. Skill Practice 18. If 60% of the 35 students in an Algebra class are women, find the number of women. Example 8 Applying Percentages A couple leaves a 15% tip for a \$32 dinner. Find the amount of the tip. Solution: The tip is 15% of \$32. 0.15 ϫ 32 ϭ 4.80 The tip is \$4.80. Skill Practice 19. The sales tax rate for one county is 6%. Find the amount of sales tax on a \$52.00 fishing pole. In some applications, it is necessary to convert a fractional part of a whole to a percent of the whole. Example 9 Finding a Percentage Union College in Schenectady, NY, accepts approximately 520 students each year from 3500 applicants. What percent does 520 represent? Round to the nearest tenth of a percent. Solution: 520 Ϸ 0.149 Convert the fractional part of the total number 3500 of applicants to decimal form. ϭ 0.149 ϫ 100% Convert the decimal to a percent. ϭ 14.9% Simplify. Approximately 14.9% of the applicants to Union College are accepted. Skill Practice 20. Eduardo answered 66 questions correctly on a test with 75 questions. What Skill Practice Answers percent of the questions does 66 represent? 18. 21 women 19. \$3.12 20. 88%
• miL28711_ch00_001-048 9/20/06 11:01 AM Page 29 BA CONFIRMING PAGES Section R.3 Decimals and Percents 29 Calculator Connections Calculators can display only a limited number of digits on the calculator screen. Therefore, repeating decimals and terminating decimals with a large number of digits will be truncated or rounded to fit the calculator display. For example, the fraction 2 ϭ 0.6 may be entered into the calcula- 3 tor as 2 Ϭ 3 . The result may appear as 2 0.6666666667 or as 0.6666666666. The fraction 11 equals the repeating decimal 0.18. However, the cal- 2 culator converts 11 to the terminating decimal 0.1818181818. Calculator Exercises Without using a calculator, find a repeating decimal to represent each of the following fractions. Then use a calculator to confirm your answer. 4 3 1. 3. 9 22 7 5 2. 4. 11 13 Section R.3 Practice Exercises Boost your GRADE at • Practice Problems • e-Professors mathzone.com! • Self-Tests • Videos • NetTutor Concept 1: Introduction to a Place Value System For Exercises 1–12, write the name of the place value for the underlined digit. 1. 481.24 2. 1345.42 3. 2912.032 4. 4208.03 5. 2.381 6. 8.249 7. 21.413 8. 82.794 9. 32.43 10. 78.04 11. 0.38192 12. 0.89754 13. The first 10 Roman numerals are: I, II, III, IV, V, VI, VII, VIII, IX, X. Is this numbering system a place value system? Explain your answer. Concept 2: Converting Fractions to Decimals For Exercises 14–21, convert each fraction to a terminating decimal or a repeating decimal. 7 9 9 3 14. 15. 16. 17. 10 10 25 25 11 16 7 3 18. 19. 20. 21. 9 9 33 11
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 30 BA CONFIRMING PAGES 30 Chapter R Reference Concept 3: Converting Decimals to Fractions For Exercises 22–33, convert each decimal to a fraction or a mixed number. 22. 0.45 23. 0.65 24. 0.181 25. 0.273 26. 2.04 27. 6.02 28. 13.007 29. 12.003 30. 0.5 (Hint: Refer 31. 0.8 32. 1.1 33. 2.3 to Table R-1) Concept 4: Converting Percents to Decimals and Fractions For Exercises 34–43, convert each percent to a decimal and to a fraction. 34. The sale price is 30% off of the original price. 35. An HMO (health maintenance organization) pays 80% of all doctors’ bills. 36. The building will be 75% complete by spring. 37. Chan plants roses in 25% of his garden. 38. The bank pays 3 3 % interest on a checking account. 4 39. A credit union pays 4 1 % interest on a savings account. 2 40. Kansas received 15.7% of its annual rainfall in 1 week. 41. Social Security withholds 5.8% of an employee’s gross pay. 42. The world population in 2005 was 253% of the world population in 1950. 43. The cost of a home is 140% of its cost 10 years ago. 44. Explain how to convert a decimal to a percent. 45. Explain how to convert a percent to a decimal. Concept 5: Converting Decimals and Fractions to Percents For Exercises 46–57, convert the decimal to a percent. 46. 0.05 47. 0.06 48. 0.90 49. 0.70 50. 1.2 51. 4.8 52. 7.5 53. 9.3 54. 0.135 55. 0.536 56. 0.003 57. 0.002 For Exercises 58–69, convert the fraction to a percent. 3 23 9 7 58. 59. 60. 61. 50 50 2 4 5 1 5 7 62. 63. 64. 65. 8 8 16 16 5 4 14 5 66. 67. 68. 69. 6 15 15 18
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 31 BA CONFIRMING PAGES Section R.3 Decimals and Percents 31 Concept 6: Applications of Percents 70. A suit that costs \$140 is discounted by 30%. How much is the discount? 71. A community college has a 12% increase in enrollment over the previous year. If the enrollment last year was 10,800 students, how many students have enrolled this year? Enrollment 15,000 Number of Students ? 12,500 10,800 10,000 7500 5000 2500 0 Year 1 Year 2 72. Louise completed 40% of her task that takes a total of 60 hours to finish. How many hours did she complete? 73. Tom’s federal taxes amount to 27% of his income. If Tom earns \$12,500 per quarter, how much will he pay in taxes for that quarter? 74. A tip of \$7 is left on a meal that costs \$56. What percentage of the cost does the tip represent? Round to the nearest tenth of a percent. 75. José paid \$5.95 in sales tax on a textbook that costs \$85. Find the percent of the sales tax. 76. Sue saves \$37.50 each week out of her paycheck of \$625. What percent of her paycheck does her savings represent? For Exercises 77–80, refer to the graph. The pie graph shows a family budget based on a net income of \$2400 per month. 77. Determine the amount spent on rent. Monthly Budget Savings 19% 78. Determine the amount spent on car payments. Rent 33% Other 79. Determine the amount spent on utilities. 6% 80. How much more money is spent than saved? Utilities Groceries 8% 17% Car 81. By the end of the year, Felipe will have 75% of his mortgage paid. Payment If the mortgage was originally for \$90,000, how much will have 17% been paid at the end of the year? 82. A certificate of deposit (CD) earns 8% interest in 1 year. If Mr. Patel has \$12,000 invested in the CD, how much interest will he receive at the end of the year? 83. On a state exit exam, a student can answer 30% of the problems incorrectly and still pass the test. If the exam has 40 problems, how many problems can a student answer incorrectly and still pass?
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 32 BA CONFIRMING PAGES 32 Chapter R Reference Section R.4 Introduction to Geometry Concepts 1. Perimeter 1. Perimeter In this section, we present several facts and formulas that may be used through- 2. Area out the text in applications of geometry. One of the most important uses of geom- 3. Volume etry involves the measurement of objects of various shapes. We begin with an 4. Angles introduction to perimeter, area, and volume for several common shapes and 5. Triangles objects. Perimeter is defined as the distance around a figure. For example, if we were to put up a fence around a field, the perimeter would determine the amount of fencing. For a polygon (a closed figure constructed from line segments), the perimeter is the sum of the lengths of the sides. For a circle, the distance around the outside is called the circumference. Rectangle Square Triangle Circle s ᐉ r w w s s a b ᐉ c s P ϭ 2ᐉ ϩ 2w P ϭ 4s Pϭaϩbϩc Circumference: C ϭ 2∏r For a circle, r represents the length of a radius—the distance from the center to r any point on the circle. The length of a diameter, d, of a circle is twice that of a radius. Thus, d ϭ 2r. The number p is a constant equal to the ratio of the circum- ference of a circle divided by the length of a diameter, that is, p ϭ C. The value d d of p is often approximated by 3.14 or 22.7 d ϭ 2r Example 1 Finding Perimeter and Circumference Find the perimeter or circumference as indicated. Use 3.14 for p. a. Perimeter of the polygon b. Perimeter of the rectangle 2m 3.1 ft 6m 8m 5.5 ft 4m 3m c. Circumference of the circle 12 cm Solution: a. P ϭ 18 m2 ϩ 12 m2 ϩ 16 m2 ϩ 14 m2 ϩ 13 m2 Add the lengths of the sides. ϭ 23 m The perimeter is 23 m.
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 33 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 33 b. P ϭ 2ᐉ ϩ 2w ϭ 2 15.5 ft2 ϩ 2 13.1 ft2 Substitute ᐉ ϭ 5.5 ft and w ϭ 3.1 ft. ϭ 11 ft ϩ 6.2 ft ϭ 17.2 ft The perimeter is 17.2 ft. c. C ϭ 2pr ϭ 2 13.14216 cm2 TIP: If a calculator is Substitute 3.14 for p and r ϭ 6 cm. used to find the ϭ 6.2816 cm2 circumference of a circle, use the p key to get a ϭ 37.68 cm The circumference is 37.68 cm. more accurate answer than by using 3.14. Skill Practice 1. Find the perimeter. 2. Find the circumference. Use 3.14 for p. 12 in. 2 in. 5 in. 5 in. 7 in. 3. Find the perimeter of the square. 2.1 yd 2. Area The area of a geometric figure is the number of square units that can be enclosed within the figure. 1 in.2 For example, the rectangle shown in Figure R-7 2 in. encloses 6 square inches (6 in.2). In applications, Area ϭ 6 in.2 we would find the area of a region if we were lay- ing carpet or putting down sod for a lawn. 3 in. The formulas used to compute the area for Figure R-7 several common geometric shapes are given here: Rectangle Square Parallelogram Triangle Trapezoid Circle s ᐉ b2 h h r w w s s h ᐉ b b b1 s A ϭ ᐉw A ϭ s2 A ϭ bh A ϭ 1 bh 2 A ϭ 1 (b1 ϩ b2)h 2 A ϭ ∏r 2 Example 2 Finding Area Find the area enclosed by each figure. a. 2 1 in. b. 10 yd 2 3 yd 4 1 in. 4 Skill Practice Answers 1. 29 in. 2. 12.56 in. 16 yd 3. 8.4 yd
• miL28711_ch00_001-048 9/20/06 09:27 AM Page 34 BA CONFIRMING PAGES 34 Chapter R Reference Solution: a. A ϭ bh The figure is a parallelogram. ϭ 14 1 4 in.212 1 2 in.2 Substitute b ϭ 4 1 in. and h ϭ 2 1 in. 4 2 ϭa in.b a in.b 17 5 TIP: Notice that the 4 2 units of area are given in square units such 85 2 ϭ in. or 10 5 in.2 8 as square inches (in.2), 8 square feet (ft2), square yards (yd2), square 1b ϩ b2 2h 1 centimeters (cm2), b. A ϭ The figure is a trapezoid. and so on. 2 1 116 yd ϩ 10 yd213 yd2 1 ϭ Substitute b1 ϭ 16 yd, b2 ϭ 10 yd, and 2 h ϭ 3 yd. 126 yd213 yd2 1 ϭ 2 ϭ 113 yd213 yd2 ϭ 39 yd2 The area is 39 yd2. Skill Practice Find the area enclosed by the figure. 4. 3 5. 4 cm 5m 3 4 cm 12 m TIP: Notice that several of the formulas presented thus far involve multiple operations. The order in which we perform the arithmetic is called the order of operations and is covered in detail in Section 1.2. We will follow these guidelines in the order given below: 1. Perform operations within parentheses first. 2. Evaluate expressions with exponents. 3. Perform multiplication or division in order from left to right. 4. Perform addition or subtraction in order from left to right. Example 3 Finding Area of a Circle Find the area of a circular fountain if the radius is 25 ft. Use 3.14 for p. 25 ft Solution: A ϭ pr 2 ϭ 13.142125 ft2 2 Substitute 3.14 for p and r ϭ 25 ft. ϭ 13.1421625 ft 2 2 Note: (25 ft)2 ϭ (25 ft)(25 ft) ϭ 625 ft2 Skill Practice Answers ϭ 1962.5 ft2 The area of the fountain is 1962.5 ft2. 9 2 4. cm2 5. 30 m 16
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 35 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 35 Skill Practice Find the area of the circular region. Use 3.14 for p. 6. 10 in. 3. Volume The volume of a solid is the number of cubic units that can be enclosed within a solid. The solid shown in Figure R-8 contains 18 cubic inches (18 in.3). In applica- tions, volume might refer to the amount of water in a swimming pool. 1 in.3 Volume ϭ 18 in.3 2 in. 3 in. 3 in. Figure R-8 The formulas used to compute the volume of several common solids are given here: Rectangular Solid Cube Right Circular Cylinder h s h w ᐉ s r s V ϭ ᐉwh V ϭ s3 V ϭ ∏r 2h TIP: Notice that the volume formulas for the three figures just shown are given by the product of the area of the base and the height of the figure: V ϭ / wh Vϭsؒsؒs V ϭ p r 2h Area of Area of Area of Rectangular Base Square Base Circular Base Right Circular Cone Sphere r h r Skill Practice Answers V ϭ 1 ∏r 2h 3 V ϭ 4 ∏r 3 3 6. 314 in.2
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 36 BA CONFIRMING PAGES 36 Chapter R Reference Example 4 Finding Volume Find the volume of each object. a. b. 1 1 ft 2 h ϭ 12 cm r ϭ 4 cm 1 1 ft 2 1 1 ft 2 Solution: a. V ϭ s3 The object is a cube. ϭ 11 1 2 ft2 3 Substitute s ϭ 11 ft. 2 3 ϭ a ftb 3 2 ϭ a ftb a ftb a ftb 3 3 3 2 2 2 27 3 ϭ ft , or 3 3 ft3 8 8 TIP: Notice that the units of volume are cubic units such as cubic inches (in.3), cubic feet (ft3), cubic yards (yd3), cubic centimeters (cm3), and so on. 1 b. V ϭ pr 2h The object is a right circular cone. 3 13.14214 cm2 2 112 cm2 1 ϭ Substitute 3.14 for p, r ϭ 4 cm, and 3 h ϭ 12 cm. 13.142116 cm2 2112 cm2 1 ϭ 3 ϭ 200.96 cm3 Skill Practice 7. Find the volume of the object. 8 ft 4 ft 4 ft 8. Find the volume of the object. Use 3.14 for p. Round to the nearest whole unit. r ϭ 2 in. Skill Practice Answers 7. 128 ft 3 8. 33 in.3
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 37 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 37 Example 5 Finding Volume in an Application An underground gas tank is in the shape of a right circular cylinder. 1 ft a. Find the volume of the tank. Use 3.14 for p. 10 ft b. Find the cost to fill the tank with gasoline if gasoline costs \$9/ft3. Solution: a. V ϭ pr 2h ϭ 13.14211 ft2 2 110 ft2 Substitute 3.14 for p, r ϭ 1 ft, and h ϭ 10 ft. ϭ 13.14211 ft2 2110 ft2 ϭ 31.4 ft3 The tank holds 31.4 ft3 of gasoline. b. Cost ϭ 1\$9/ft3 2131.4 ft3 2 ϭ \$282.60 It will cost \$282.60 to fill the tank. Skill Practice 9a. Find the volume of soda in the can. Use 3.14 for p. Round to the nearest whole unit. b. Using your answer from part (a), how much soda is con- 12 cm tained in a six-pack? 6 cm 4. Angles Applications involving angles and their measure come up often in the study of algebra, trigonometry, calculus, and applied sciences. The most common unit used to measure an angle is the degree 1°2. Several angles and their corresponding degree measure are shown in Figure R-9. 180Њ 90Њ Straight Right Acute Obtuse Angle Angle Angle Angle Figure R-9 • An angle that measures 90° is a right angle (right angles are often marked with a square or corner symbol, ٗ). • An angle that measures 180° is called a straight angle. • An angle that measures between 0° and 90° is called an acute angle. • An angle that measures between 90° and 180° is called an obtuse angle. • Two angles with the same measure are equal angles (or congruent angles). Skill Practice Answers 9a. 339 cm3 b. 2034 cm3
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 38 BA CONFIRMING PAGES 38 Chapter R Reference The measure of an angle will be denoted by the symbol m written in front of the angle. Therefore, the measure of ЄA is denoted m1ЄA2. • Two angles are said to be • Two angles are said to be complementary if the sum of supplementary if the sum of their measures is 90°. their measures is 180°. y y x x m(∠ x) ϩ m(∠y) ϭ 90Њ m(∠ x) ϩ m(∠y) ϭ 180Њ When two lines intersect, four angles are formed (Figure R-10). In Figure R-10, Єa and Єb are vertical angles. Another set of vertical angles is the pair Єc and Єd. An important property of vertical angles is that the measures of two vertical angles are equal. In the figure, m1Єa2 ϭ m1Єb2 and m1Єc2 ϭ m1Єd2. Parallel lines are lines that lie in the same plane and do not intersect. In Figure R-11, the lines L1 and L2 are parallel lines. If a line intersects two parallel lines, the line is called a transversal. In Figure R-11, the line m is a transversal and forms eight angles with the parallel lines L1 and L2. 1 2 L1 b 3 4 c d 5 6 a L2 7 8 m Figure R-10 Figure R-11 The angles 1–8 in Figure R-11 have special names and special properties. Two angles that lie between the parallel lines (interior) and on alternate sides of the transversal are called alternate interior angles. Pairs of alternate interior angles are shown next. L1 L1 3 4 6 L2 5 L2 Є3 and Є6 Є4 and Є5 Alternate interior angles are equal in measure. Thus, m1Є32 ϭ m1Є62 and m1Є42 ϭ m1Є52.
• miL28711_ch00_001-048 9/20/06 06:52 AM Page 39 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 39 Two angles that lie outside the parallel lines (exterior) and on alternate sides of the transversal are called alternate exterior angles. Pairs of alternate exterior angles are shown here. 1 2 L1 L1 L2 L2 8 7 Є1 and Є8 Є2 and Є7 Alternate exterior angles are equal in measure. Thus, m1Є12 ϭ m1Є82 and m1Є22 ϭ m1Є72. Two angles that lie on the same side of the transversal such that one is exterior and one is interior are called corresponding angles. Corresponding angles cannot be adjacent to each other. Pairs of corresponding angles are shown here in color. 1 2 L1 3 4 5 6 L2 7 8 Corresponding angles are equal in measure. Thus, m1Є12 ϭ m1Є52, m1Є22 ϭm1Є62, m1Є32 ϭ m1Є72, and m1Є42 ϭ m1Є82. Example 6 Finding Unknown Angles in a Diagram m Find the measure of each angle and explain how the angle is related to the given angle of 70°. d 70Њ L1 c a. Єa b. Єb c. Єc d. Єd a L2 b Solution: a. m1Єa2 ϭ 70° Єa is a corresponding angle to the given angle of 70°. b. m1Єb2 ϭ 70° Єb and the given angle of 70° are alternate exterior angles. c. m1Єc2 ϭ 70° Єc and the given angle of 70° are vertical angles. d. m1Єd2 ϭ 110° Єd is the supplement of the given angle of 70°. Skill Practice 10. Refer to the figure. Assume that lines m L1 and L 2 are parallel. Given that m 1Є32 ϭ 23°, find: 1 2 L1 3 4 a. m 1Є22 b. m 1Є42 5 6 c. m 1Є52 d. m 1Є82 L2 7 8 Skill Practice Answers 10a. 23° b. 157° c. 157° d. 157°
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 40 BA CONFIRMING PAGES 40 Chapter R Reference 5. Triangles Triangles are categorized by the measures of the angles (Figure R-12) and by the number of equal sides or angles (Figure R-13). • An acute triangle is a triangle in which all three angles are acute. • A right triangle is a triangle in which one angle is a right angle. • An obtuse triangle is a triangle in which one angle is obtuse. Acute Right Obtuse Triangle Triangle Triangle Figure R-12 • An equilateral triangle is a triangle in which all three sides (and all three an- gles) are equal in measure. • An isosceles triangle is a triangle in which two sides are equal in measure (the angles opposite the equal sides are also equal in measure). • A scalene triangle is a triangle in which no sides (or angles) are equal in measure. Equilateral Isosceles Scalene Triangle Triangle Triangle Figure R-13 The following important property is true for all triangles. Sum of the Angles in a Triangle The sum of the measures of the angles of a triangle is 180°. Example 7 Finding Unknown Angles in a Diagram Find the measure of each angle in the figure. a. Єa d b. Єb c. Єc d. Єd 40Њ e. Єe 110Њ e a c b
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 41 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 41 Solution: a. m1Єa2 ϭ 30° The sum of the angles in a triangle is 180°. b. m1Єb2 ϭ 30° Єa and Єb are vertical angles and are equal in measure. c. m1Єc2 ϭ 150° Єc and Єa are supplementary angles 1Єc and Єb are also supplementary). d. m1Єd2 ϭ 40° Єd and the given angle of 40° are vertical angles. e. m1Єe2 ϭ 70° Єe and the given angle of 110° are supplementary angles. Skill Practice 11. Refer to the figure. Find the measure of the indicated angle. a. Єa b. Єb c. Єc c 130Њ b a 100Њ Skill Practice Answers 11a. 80° b. 50° c. 50° Section R.4 Practice Exercises Boost your GRADE at • Practice Problems • e-Professors mathzone.com! • Self-Tests • Videos • NetTutor Concept 1: Perimeter 1. Identify which of the following units could be measures of perimeter. a. Square inches (in.2) b. Meters (m) c. Cubic feet (ft3) d. Cubic meters (m3) e. Miles (mi) f. Square centimeters (cm2) g. Square yards (yd2) h. Cubic inches (in.3) i. Kilometers (km) For Exercises 2–5, find the perimeter of each figure. 2. 3. 4. 5. 6m 22 cm 4.3 mi 0.25 ft 10 m 32 cm 4.3 mi 0.25 ft
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 42 BA CONFIRMING PAGES 42 Chapter R Reference 6. Identify which of the following units could be measures of circumference. a. Square inches (in.2) b. Meters (m) c. Cubic feet (ft3) d. Cubic meters (m3) e. Miles (mi) f. Square centimeters (cm2) g. Square yards (yd2) h. Cubic inches (in.3) i. Kilometers (km) For Exercises 7–10, find the perimeter or circumference. Use 3.14 for p. 7. 8. 5 cm 1 9. 10. 1 2 3 in. 4 in. 3 2 cm 4.2 yd 10 ft 1 1 6 4 cm 5 6 in. Concept 2: Area 11. Identify which of the following units could be measures of area. a. Square inches (in.2) b. Meters (m) c. Cubic feet (ft3) d. Cubic meters (m3) e. Miles (mi) f. Square centimeters (cm2) g. Square yards (yd2) h. Cubic inches (in.3) i. Kilometers (km) For Exercises 12–25, find the area. Use 3.14 for p. 12. 13. 14. 5 ft 4.1 m 11 cm 8 ft 4.1 m 3 cm 15. 16. 17. 6 in. 0.01 m 6.1 in. 14 in. 0.04 m 6.1 in. 18. 19. 20. 5 mi 2.3 km 4.2 ft 16 mi 8.8 km 21. 22. 8 in. 23. 6.5 cm 6 in. 6 in. 14 in. 14 in. 8 in.
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 43 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 43 24. 9 ft 25. 4 km 3 km 7 ft Concept 3: Volume 26. Identify which of the following units could be measures of volume. a. Square inches (in.2) b. Meters (m) c. Cubic feet (ft3) d. Cubic meters (m3) e. Miles (mi) f. Square centimeters (cm2) g. Square yards (yd2) h. Cubic inches (in.3) i. Kilometers (km) For Exercises 27–34, find the volume of each figure. Use 3.14 for p. 27. 3.3 cm 28. 2 ft 29. 4 in. 6.2 cm 6 ft 11 in. 2 6 1 in. 2 30. 31. r ϭ 3 cm 32. d ϭ 12 ft 2 1 cm 8 2 cm 5 3 cm 4 33. 9 cm 34. 4 ft 20 cm 6 ft 35. A florist sells balloons and needs to know how much helium to order. Each balloon is approximately spherical with a radius of 9 in. How much helium is needed to fill one balloon? 36. Find the volume of a spherical ball whose radius is 3 in. Use 3.14 for p. 37. Find the volume of a snow cone in the shape of a right circular cone whose radius is 3 cm and whose height is 12 cm. Use 3.14 for p. 38. A landscaping supply company has a pile of gravel in the shape of a right circular cone whose radius is 10 yd and whose height is 18 yd. Find the volume of the gravel. Use 3.14 for p. 39. Find the volume of a cube that is 3.2 ft on a side. 40. Find the volume of a cube that is 10.5 cm on a side.
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 44 BA CONFIRMING PAGES 44 Chapter R Reference Mixed Exercises: Perimeter, Area, and Volume 41. A wall measuring 20 ft by 8 ft can be painted for \$50. a. What is the price per square foot? Round to the nearest cent. b. At this rate, how much would it cost to paint the remaining three walls that measure 20 ft by 8 ft, 16 ft by 8 ft, and 16 ft by 8 ft? Round to the nearest dollar. 42. Suppose it costs \$320 to carpet a 16 ft by 12 ft room. a. What is the price per square foot? Round to the nearest cent. b. At this rate, how much would it cost to carpet a room that is 20 ft by 32 ft? 43. If you were to purchase fencing for a garden, would you measure the perimeter or area of the garden? 44. If you were to purchase sod (grass) for your front yard, would you measure the perimeter or area of the yard? 45. a. Find the area of a circular pizza that is 8 in. in diameter (the radius is 4 in.). Use 3.14 for p. b. Find the area of a circular pizza that is 12 in. in diameter (the radius is 6 in.). c. Assume that the 8-in. diameter and 12-in. diameter pizzas are both the same thickness. Which would provide more pizza, two 8-in. pizzas or one 12-in. pizza? 46. Find the area of a circular stained glass window that is 16 in. in diameter. Use 3.14 for p. 47. Find the volume of a soup can in the shape of a right circular cylinder if its radius is 3.2 cm and its height is 9 cm. Use 3.14 for p. 48. Find the volume of a coffee mug whose radius is 2.5 in. and whose height is 6 in. Use 3.14 for p. Concept 4: Angles For Exercises 49–56, answer True or False. If an answer is false, explain why. 49. The sum of the measures of two right angles equals the measure of a straight angle. 50. Two right angles are complementary. 51. Two right angles are supplementary. 52. Two acute angles cannot be supplementary. 53. Two obtuse angles cannot be supplementary. 54. An obtuse angle and an acute angle can be supplementary. 55. If a triangle is equilateral, then it is not scalene. 56. If a triangle is isosceles, then it is also scalene. 57. What angle is its own complement? 58. What angle is its own supplement? 59. If possible, find two acute angles that are supplementary.
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 45 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 45 60. If possible, find two acute angles that are complementary. Answers may vary. 61. If possible, find an obtuse angle and an acute angle that are supplementary. Answers may vary. 62. If possible, find two obtuse angles that are supplementary. 63. Refer to the figure. 1 a. State all the pairs of vertical angles. 4 2 3 b. State all the pairs of supplementary angles. c. If the measure of Є4 is 80°, find the measures of Є1, Є2, and Є3. 64. Refer to the figure. a. State all the pairs of vertical angles. b c b. State all the pairs of supplementary angles. a d c. If the measure of Єa is 25°, find the measures of Єb, Єc, and Єd. For Exercises 65–68, find the complement of each angle. 65. 33° 66. 87° 67. 12° 68. 45° For Exercises 69–72, find the supplement of each angle. 69. 33° 70. 87° 71. 122° 72. 90° For Exercises 73–80, refer to the figure. Assume that L1 and L2 are n parallel lines cut by the transversal, n. 73. m1Є52 ϭ m1Є 2 Reason: Vertical angles have L1 1 2 equal measures. 4 3 74. m1Є52 ϭ m1Є 2 Reason: Alternate interior angles have equal measures. L2 5 6 2 8 7 75. m1Є52 ϭ m1Є Reason: Corresponding angles have equal measures. 76. m1Є72 ϭ m1Є 2 Reason: Corresponding angles have equal measures. 77. m1Є72 ϭ m1Є 2 Reason: Alternate exterior angles have equal measures. 78. m1Є72 ϭ m1Є 2 Reason: Vertical angles have equal measures. 79. m1Є32 ϭ m1Є 2 Reason: Alternate interior angles have L1 equal measures. L2 80. m1Є32 ϭ m1Є 2 Reason: Vertical angles have equal measures. 81. Find the measures of angles a–g in the figure. Assume that L1 and L2 135Њ a d e n are parallel and that n is a transversal. c b g f
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 46 BA CONFIRMING PAGES 46 Chapter R Reference 82. Find the measures of angles a–g in the figure. Assume that L1 and L2 are parallel and that n is a transversal. n c 65Њ a L1 b e d g f L2 Concept 5: Triangles For Exercises 83–86, identify the triangle as equilateral, isosceles, or scalene. 83. 84. 10 in. 6 in. 6 cm 6 cm 8 in. 6 cm 85. 6m 6m 86. 15 ft 7 ft 10 m 9 ft 87. Can a triangle be both a right triangle and an obtuse triangle? Explain. 88. Can a triangle be both a right triangle and an isosceles triangle? Explain. For Exercises 89–92, find the measures of the missing angles. 89. 90. ? ? 40Њ 50Њ 20Њ 120Њ 91. ? 92. 53Њ 27Њ b ? c d a 93. Refer to the figure. Find the measures of angles a–j. f 65Њ e g 35Њ i j h
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 47 BA CONFIRMING PAGES Section R.4 Introduction to Geometry 47 94. Refer to the figure. Find the measures of angles a–j. i h j 20Њ b 120Њ a c d f e g 95. Refer to the figure. Find the measures of angles a–k. Assume that L1 and L2 are parallel. k 70Њ c L1 j 45Њ d a b h e f L2 g i 96. Refer to the figure. Find the measures of angles a–k. Assume that L1 and L2 are parallel. L1 L2 k j b c d 75Њ a e f 40Њ i h g
• miL28711_ch00_001-048 9/20/06 06:53 AM Page 48 BA CONFIRMING PAGES 48 Chapter R Reference Expanding Your Skills For Exercises 97–98, find the perimeter. 97. 98. 5.1 ft 5 ft 4.2 ft 14.1 ft 16 ft 15.8 ft 20 ft For Exercises 99–102, find the area of the shaded region. Use 3.14 for ␲. 99. 100. 3 ft 8 ft 8 in. 10 in. 5 ft 8 in. 11 ft 10 in. 101. 102. 1.8 cm 4.1 cm 2.5 in. 3 in. 6.2 cm 4 in.
• miL28711_ch01_049-120 11:15:2006 07:59 Page 49 BA CONFIRMING PAGES The Set of Real Numbers 1.1 Sets of Numbers and the Real Number Line 1 1.2 Order of Operations 1.3 Addition of Real Numbers 1.4 Subtraction of Real Numbers Problem Recognition Exercises—Addition and Subtraction of Signed Numbers 1.5 Multiplication and Division of Real Numbers 1.6 Properties of Real Numbers and Simplifying Expressions In Chapter 1 we present operations on real numbers. To be successful in algebra, it is particularly important to understand the order of operations. As you work through the chapter, pay attention to the order of operations. Then work through this puzzle. When you fill in the blanks, notice that nega- tive signs may appear to the left of a horizontal number. They may also appear above a number written vertically. Across 2. Ϫ122 1 5. Ϫ3426 Ϫ 469 ϩ 124 Ϫ 6421 2 3 9. Ϫ2.5 Ϫ 1.4 Ϫ 8.1 Ϫ 100 11. 243 Ϫ ƒ 12 Ϫ 17 ƒ ϩ ƒ Ϫ600 ƒ 4 125 Ϫ 9 12. 155 Ϫ 312 Ϫ 4 2 Ϫ 411 Ϫ 32 2 2 5 6 7 Down 8 1. 1Ϫ122 2 3. 120 Ϫ Ϫ2 9 10 4. 600 Ϭ 323 ϩ 7 Ϫ 14 ϩ 12 4 11 120 Ϫ 125 Ϫ 9 6. Ϫ Ϫ aϪ b ϩ 15 Ϫ 4 11 1 3 6 2 7. 841Ϫ122 Ϫ 1Ϫ10,6252 12 8. Ϫ2 10. 1Ϫ2.521Ϫ1.421Ϫ8.121Ϫ1002 49
• miL28711_ch01_049-120 9/20/06 11:33 AM Page 50 BA CONFIRMING PAGES 50 Chapter 1 The Set of Real Numbers Section 1.1 Sets of Numbers and the Real Number Line Concepts 1. Real Number Line 1. Real Number Line The numbers we work with on a day-to-day basis are all part of the set of real 2. Plotting Points on the numbers. The real numbers encompass zero, all positive, and all negative num- Number Line bers, including those represented by fractions and decimal numbers. The set of 3. Set of Real Numbers real numbers can be represented graphically on a horizontal number line with 4. Inequalities a point labeled as 0. Positive real numbers are graphed to the right of 0, and 5. Opposite of a Real Number negative real numbers are graphed to the left. Zero is neither positive nor neg- 6. Absolute Value of a ative. Each point on the number line corresponds to exactly one real number. Real Number For this reason, this number line is called the real number line (Figure 1-1). Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 Negative numbers Positive numbers Figure 1-1 2. Plotting Points on the Number Line Example 1 Plotting Points on the Real Number Line Plot the points on the real number line that represent the following real numbers. 3 16 a. Ϫ3 b. c. Ϫ4.8 d. 2 5 Solution: a. Because Ϫ3 is negative, it lies three units to the left of zero. b. The fraction 3 can be expressed as the mixed number 11, which lies halfway 2 2 between 1 and 2 on the number line. c. The negative number Ϫ4.8 lies 10 units to the left of Ϫ4 on the number line. 8 d. The fraction 16 can be expressed as the mixed number 31, which lies 1 unit to 5 5 5 the right of 3 on the number line. 3 16 Ϫ4.8 Ϫ3 2 5 Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6 Skill Practice 1. Plot the numbers on a real number line. {Ϫ1, Ϫ2.5, 4, 4} 3 0 3. Set of Real Numbers Skill Practice Answers 1. Ϫ2.5 In mathematics, a well-defined collection of elements is called a set. “Well- Ϫ1 3 4 4 defined” means the set is described in such a way that it is clear whether an Ϫ5Ϫ4Ϫ3Ϫ2Ϫ1 0 1 2 3 4 5
• miL28711_ch01_049-120 9/20/06 11:33 AM Page 51 BA CONFIRMING PAGES Section 1.1 Sets of Numbers and the Real Number Line 51 element is in the set. The symbols 5 6 are used to enclose the elements of the set. For example, the set 5A, B, C, D, E6 represents the set of the first five letters of the alphabet. Several sets of numbers are used extensively in algebra and are subsets (or part) of the set of real numbers. These are: The set of natural numbers The set of whole numbers The set of integers The set of rational numbers The set of irrational numbers Definition of the Natural Numbers, Whole Numbers, and Integers The set of natural numbers is 51, 2, 3, . . .6 The set of whole numbers is 50, 1, 2, 3, . . .6 The set of integers is 5. . . Ϫ3, Ϫ2, Ϫ1, 0, 1, 2, 3, . . .6 Notice that the set of whole numbers includes the natural numbers. Therefore, every natural number is also a whole number. The set of integers includes the set of whole numbers. Therefore, every whole number is also an integer. The rela- tionship among the elements of the natural numbers, whole numbers, and integers is shown in Figure 1-2. Integers Ϫ3, Ϫ2, Ϫ1 Ϫ5, Ϫ4, . . . , Ϫ6 Whole numbers 0 Natural numbers 1, 2, 3, 4, . . . Figure 1-2 Fractions are also among the numbers we use frequently. A number that can be written as a fraction whose numerator is an integer and whose denominator is a nonzero integer is called a rational number. Definition of the Rational Numbers The set of rational numbers is the set of numbers that can be expressed in p the form q, where both p and q are integers and q does not equal 0. p We also say that a rational number q is a ratio of two integers, p and q, where q is not equal to zero.
• miL28711_ch01_049-120 9/20/06 11:33 AM Page 52 BA CONFIRMING PAGES 52 Chapter 1 The Set of Real Numbers Example 2 Identifying Rational Numbers Show that the following numbers are rational numbers by finding an equivalent ratio of two integers. Ϫ2 a. b. Ϫ12 c. 0.5 d. 0.6 3 Solution: a. The fraction Ϫ2 is a rational number because it can be expressed as the 3 ratio of Ϫ2 and 3. b. The number Ϫ12 is a rational number because it can be expressed as the ratio of Ϫ12 and 1, that is, Ϫ12 ϭ Ϫ12. In this example, we see that an 1 integer is also a rational number. c. The terminating decimal 0.5 is a rational number because it can be expressed as the ratio of 5 and 10. That is, 0.5 ϭ 10. In this example we 5 see that a terminating decimal is also a rational number. d. The repeating decimal 0.6 is a rational number because it can be expressed as the ratio of 2 and 3. That is, 0.6 ϭ 2. In this example we see 3 that a repeating decimal is also a rational number. Skill Practice Show that each number is rational by finding an equivalent ratio of two integers. 3 2. 3. Ϫ5 4. 0.3 5. 0.3 7 TIP: Any rational number can be represented by a terminating decimal or by a repeating decimal. repeated pattern. Another example of an irrational number is 13 (read as “the Some real numbers, such as the number p, cannot be represented by the ratio positive square root of 3”). The expression 13 is a number that when multiplied of two integers. In decimal form, an irrational number is a nonterminating, non- by itself is 3. There is no rational number that satisfies this condition. Thus, 13 is repeating decimal. The value of p, for example, can be approximated as p Ϸ 3.1415926535897932. However, the decimal digits continue forever with no an irrational number. Definition of the Irrational Numbers The set of irrational numbers is the set of real numbers that are not rational. Note: An irrational number cannot be written as a terminating decimal or as a repeating decimal. Skill Practice Answers The set of real numbers consists of both the rational and the irrational 2. ratio of 3 and 7 numbers. The relationship among these important sets of numbers is illustrated in 3. ratio of Ϫ5 and 1 4. ratio of 3 and 10 Figure 1-3: 5. ratio of 1 and 3
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 53 BA CONFIRMING PAGES Section 1.1 Sets of Numbers and the Real Number Line 53 Real Numbers Rational Irrational numbers 0.25 numbers Ϫ2 0.3 √2 7 Integers . . . Ϫ3, Ϫ2, Ϫ1 Ϫ √17 ␲ Whole numbers 0 Natural numbers 1, 2, 3, . . . Figure 1-3 Example 3 Classifying Numbers by Set Check the set(s) to which each number belongs. The numbers may belong to more than one set. Natural Whole Rational Irrational Real Numbers Numbers Integers Numbers Numbers Numbers 5 17 Ϫ47 3 1.48 0 Solution: Natural Whole Rational Irrational Real Numbers Numbers Integers Numbers Numbers Numbers 5 ✔ ✔ ✔ ✔ (ratio of 5 ✔ and 1) Ϫ47 ✔ (ratio of ✔ 3 Ϫ47 and 3) 17 ✔ (ratio of ✔ 1.48 148 and 100) ✔ ✔ 0 ✔ ✔ ✔ (ratio of 0 ✔ and 1)
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 54 BA CONFIRMING PAGES 54 Chapter 1 The Set of Real Numbers 8. 113 Skill Practice Identify the sets to which each number belongs. Choose from: natural numbers, whole numbers, integers, rational numbers, irrational numbers, and real numbers. 6. Ϫ4 7. 0.7 9. 12 10. 0 4. Inequalities The relative size of two real numbers can be compared using the real number line. Suppose a and b represent two real numbers. We say that a is less than b, denoted a 6 b, if a lies to the left of b on the number line. a b aϽb We say that a is greater than b, denoted a 7 b, if a lies to the right of b on the number line. b a aϾb Table 1-1 summarizes the relational operators that compare two real numbers a and b. Table 1-1 Mathematical Expression Translation Example a 6 b a is less than b. 2 6 3 a 7 b a is greater than b. 5 7 1 aՅb a is less than or equal to b. 4Յ4 aՆb a is greater than or equal to b. 10 Ն 9 aϭb a is equal to b. 6ϭ6 a b a is not equal to b. 7 0 aϷb a is approximately equal to b. 2.3 Ϸ 2 The symbols 6 , 7, Յ, Ն, and are called inequality signs, and the expressions a 6 b, a 7 b, a Յ b, a Ն b, and a b are called inequalities. Example 4 Ordering Real Numbers The average temperatures (in degrees Celsius) for selected cities in the United States and Canada in January are shown in Table 1-2. Table 1-2 City Temp (؇C) Skill Practice Answers Prince George, British Columbia Ϫ12.1 6. integers, rational numbers, real Corpus Christi, Texas 13.4 numbers 7. rational numbers, real numbers Parkersburg, West Virginia Ϫ0.9 8. irrational numbers, real numbers San Jose, California 9.7 9. natural numbers, whole numbers, integers, rational numbers, real Juneau, Alaska Ϫ5.7 numbers New Bedford, Massachusetts Ϫ0.2 10. whole numbers, integers, rational Durham, North Carolina 4.2 numbers, real numbers
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 55 BA CONFIRMING PAGES Section 1.1 Sets of Numbers and the Real Number Line 55 a. Plot a point on the real number line representing the temperature of each city. b. Compare the temperatures between the following cities, and fill in the blank with the appropriate inequality sign: 6 or 7. Solution: Corpus Christi Prince George New Bedford Parkersburg San Jose Durham Juneau Ϫ15 Ϫ10 Ϫ5 0 5 10 15 a. Temperature of San Jose Ͻ temperature of Corpus Christi b. Temperature of Juneau Ͼ temperature of Prince George c. Temperature of Parkersburg Ͻ temperature of New Bedford d. Temperature of Parkersburg Ͼ temperature of Prince George Skill Practice Based on the location of the numbers on the number line, fill in the blanks with the appropriate inequality sign: 6 or 7. k b x 11. k ________ x 12. x ________ b 13. b ________ k 5. Opposite of a Real Number To gain mastery of any algebraic skill, it is necessary to know the meaning of key definitions and key symbols. Two important definitions are the opposite of a real number and the absolute value of a real number. Definition of the Opposite of a Real Number Two numbers that are the same distance from 0 but on opposite sides of 0 on the number line are called opposites of each other. Symbolically, we denote the opposite of a real number a as Ϫa. Example 5 Finding the Opposite of a Real Number a. Find the opposite of 5. b. Find the opposite of Ϫ4. 7 c. Evaluate Ϫ10.462. d. Evaluate Ϫ1Ϫ11 2. 3 Skill Practice Answers 11. 6 12. 7 13. 7
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 56 BA CONFIRMING PAGES 56 Chapter 1 The Set of Real Numbers Solution: a. The opposite of 5 is Ϫ5. 4 4 b. The opposite of Ϫ is . 7 7 opposites Ϫ4 7 4 7 Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6 opposites c. Ϫ10.462 ϭ Ϫ0.46 The expression Ϫ10.462 represents the opposite of 0.46. bϭ The expression Ϫ1Ϫ11 2 represents the opposite of Ϫ11. 11 11 d. ϪaϪ 3 3 3 3 Skill Practice 14. Find the opposite of 224. 15. Find the opposite of Ϫ3.4. 17. Evaluate Ϫa b. 1 16. Evaluate Ϫ1Ϫ222. 5 6. Absolute Value of a Real Number The concept of absolute value will be used to define the addition of real numbers in Section 1.3. Informal Definition of the Absolute Value of a Real Number The absolute value of a real number a, denoted 0a 0 , is the distance between a and 0 on the number line. Note: The absolute value of any real number is nonnegative. For example, 0 3 0 ϭ 3 and 0 Ϫ3 0 ϭ 3. 3 units 3 units Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6 Example 6 Finding the Absolute Value of a Real Number Evaluate the absolute value expressions. a. 0Ϫ4 0 b. 0 1 0 2 c. 0 Ϫ6.2 0 d. 00 0 Solution: a. 0Ϫ4 0 ϭ 4 Ϫ4 is 4 units from 0 on the number line. Skill Practice Answers 14. Ϫ224 15. 3.4 1 16. 22 17. Ϫ 5
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 57 BA CONFIRMING PAGES Section 1.1 Sets of Numbers and the Real Number Line 57 b. 0 1 0 ϭ 1 2 2 1 2 is 1 2 unit from 0 on the number line. c. 0Ϫ6.2 0 ϭ 6.2 Ϫ6.2 is 6.2 units from 0 on the number line. d. 00 0 ϭ 0 0 is 0 units from 0 on the number line. 1 6.2 units 2 unit Ϫ7 Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 units Skill Practice Evaluate. 18. 0 14 0 19. 0 Ϫ99 0 20. 0 0 0 21. ` Ϫ ` 7 8 The absolute value of a number a is its distance from zero on the number line. The definition of 0a 0 may also be given symbolically depending on whether a is negative or nonnegative. Definition of the Absolute Value of a Real Number Let a be a real number. Then 1. If a is nonnegative (that is, a Ն 02, then 0a 0 ϭ a. 2. If a is negative (that is, a 6 02, then 0a 0 ϭ Ϫa. This definition states that if a is a nonnegative number, then 0a 0 equals a itself. If a is a negative number, then 0 a 0 equals the opposite of a. For example, 09 0 ϭ 9 Because 9 is positive, then 0 9 0 equals the number 9 itself. 0Ϫ7 0 ϭ 7 Because Ϫ7 is negative, then 0 Ϫ7 0 equals the opposite of Ϫ7, which is 7. Example 7 Comparing Absolute Value Expressions Determine if the statements are true or false. a. 03 0 Յ 3 b. Ϫ 0 5 0 ϭ 0 Ϫ5 0 Solution: a. 03 0 Յ 3 True. The symbol Յ means “less than or equal to.” Since 0 3 0 is equal to 3, then 0 3 0 Յ 3 is a true statement. b. Ϫ 0 5 0 ϭ 0 Ϫ5 0 False. On the left-hand side, Ϫ 0 5 0 is the opposite of 0 5 0 . Hence Ϫ 0 5 0 ϭ Ϫ5. On the right-hand side, 0 Ϫ5 0 ϭ 5. Therefore, the original statement simplifies to Ϫ5 ϭ 5, which is false. Skill Practice True or False. Skill Practice Answers 23. 0 Ϫ17 0 ϭ 17 18. 14 19. 99 20. 0 22. Ϫ4 6 Ϫ4 7 21. 22. False 23. True 8
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 59 BA CONFIRMING PAGES Section 1.1 Sets of Numbers and the Real Number Line 59 Concept 2: Plotting Points on the Number Line 3. Plot the numbers on a real number line: 51, Ϫ2, Ϫp, 0, Ϫ5, 5.16 2 Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6 4. Plot the numbers on a real number line: 53, Ϫ4, 1, Ϫ1.7, Ϫ4, 1.756 8 3 Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6 Concept 3: Set of Real Numbers For Exercises 5–20, describe each number as (a) a terminating decimal, (b) a repeating decimal, or (c) a nonterminating, nonrepeating decimal. 1 1 5. 0.29 6. 3.8 7. 8. 9 3 1 1 9. 10. 11. 2p 12. 3p 19. 16 20. 110 8 5 13. Ϫ0.125 14. Ϫ3.24 15. Ϫ3 16. Ϫ6 17. 0.2 18. 0.6 21. List all of the numbers from Exercises 5–20 that are rational numbers. 22. List all of the numbers from Exercises 5–20 that are irrational numbers. 23. List three numbers that are real numbers but not rational numbers. 24. List three numbers that are real numbers but not irrational numbers. 25. List three numbers that are integers but not natural numbers. 26. List three numbers that are integers but not whole numbers. For Exercises 28–33, let A ϭ 5Ϫ3, 111, Ϫ4, 0.6, 0, 17, 16 27. List three numbers that are rational numbers but not integers. 2 28. Are all of the numbers in set A real numbers? 29. List all of the rational numbers in set A. 34. Plot the real numbers of set A on a number line. (Hint: 111 Ϸ 3.3 and 17 Ϸ 2.6) 30. List all of the whole numbers in set A. 31. List all of the natural numbers in set A. 32. List all of the irrational numbers in set A. 33. List all of the integers in set A. Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 60 BA CONFIRMING PAGES 60 Chapter 1 The Set of Real Numbers Concept 4: Inequalities LPGA Golfers Final Score with 35. The LPGA Samsung World Championship of women’s golf scores Respect to Par for selected players are given in the table. Compare the scores Annika Sorenstam 7 and fill in the blanks with the appropriate inequality sign: 6 or 7. Laura Davies Ϫ4 a. Kane’s score _______ Pak’s score. Lorie Kane 0 Cindy McCurdy 3 b. Sorenstam’s score _______ Davies’ score. Se Ri Pak Ϫ8 c. Pak’s score _______ McCurdy’s score. d. Kane’s score _______ Davies’ score. 36. The elevations of selected cities in the United States are shown in the figure. Compare the elevations and fill in the blanks with the appropriate inequality sign: 6 or 7. (A negative number Chicago indicates that the city is below sea level.) 579 ft Cincinnati a. Elevation of Tucson _______ elevation of Cincinnati. 433 ft b. Elevation of New Orleans _______ elevation of Chicago. Tucson 2250 ft New Orleans c. Elevation of New Orleans _______ elevation of Houston. Houston 0 ft Ϫ8 ft d. Elevation of Chicago _______ elevation of Cincinnati. Concept 5: Opposite of a Real Number For Exercises 37–44, find the opposite of each number. 37. 18 38. 2 39. Ϫ6.1 40. Ϫ2.5 5 1 7 1 41. Ϫ 42. Ϫ 43. 44. 8 3 3 9 The opposite of a is denoted as Ϫa. For Exercises 45–50, simplify. 47. Ϫa b 7 45. Ϫ1Ϫ32 46. Ϫ1Ϫ5.12 48. Ϫ1Ϫ72 3 49. Ϫ1Ϫ82 50. Ϫ1362 Concept 6: Absolute Value of a Real Number For Exercises 51–58, find the absolute value as indicated. 51. 0 Ϫ2 0 52. 0 Ϫ7 0 53. 0 Ϫ1.5 0 54. 0 Ϫ3.7 0 55. Ϫ 0 Ϫ1.5 0 56. Ϫ 0 Ϫ3.7 0 57. ` ` 58. ` ` 3 7 2 4 For Exercises 59–60, answer true or false. If a statement is false, explain why. 59. If n is positive, then 0n 0 is negative. 60. If m is negative, then 0 m 0 is negative. For Exercises 61–84, determine if the statements are true or false. Use the real number line to justify the answer. 61. 5 7 2 62. 8 6 10 63. 6 6 6 64. 19 7 19
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 61 BA CONFIRMING PAGES Section 1.2 Order of Operations 61 3 1 1 7 65. Ϫ7 Ն Ϫ7 66. Ϫ1 Յ Ϫ1 67. Յ 68. Ϫ Ն Ϫ 2 6 4 8 69. Ϫ5 7 Ϫ2 70. 6 6 Ϫ10 71. 8 8 72. 10 10 73. 0Ϫ2 0 Ն 0 Ϫ1 0 74. 03 0 Յ 0 Ϫ1 0 75. ` Ϫ ` ϭ ` ` 76. ` Ϫ ` ϭ ` ` 1 1 1 1 9 9 3 3 77. 07 0 0Ϫ7 0 78. 0Ϫ13 0 013 0 79. Ϫ1 6 0Ϫ1 0 80. Ϫ6 6 0Ϫ6 0 81. 0Ϫ8 0 Ն 08 0 82. 0Ϫ11 0 Ն 0 11 0 83. 0 Ϫ2 0 Յ 02 0 84. 0Ϫ21 0 Յ 021 0 Expanding Your Skills 85. For what numbers, a, is Ϫa positive? 86. For what numbers, a, is 0 a 0 ϭ a? Order of Operations Section 1.2 1. Variables and Expressions Concepts A variable is a symbol or letter, such as x, y, and z, used to represent an un- 1. Variables and Expressions known number. Constants are values that do not vary such as the numbers 2. Evaluating Algebraic 3, Ϫ1.5, 2, and p. An algebraic expression is a collection of variables and con- 7 Expressions stants under algebraic operations. For example, 3, y ϩ 7, and t Ϫ 1.4 are alge- x 3. Exponential Expressions braic expressions. 4. Square Roots The symbols used to show the four basic operations of addition, subtraction, 5. Order of Operations multiplication, and division are summarized in Table 1-3. 6. Translations Table 1-3 Operation Symbols Translation Addition aϩb sum of a and b a plus b b added to a b more than a a increased by b the total of a and b Subtraction aϪb difference of a and b a minus b b subtracted from a a decreased by b b less than a Multiplication a ϫ b, a ؒ b, a1b2, 1a2b, 1a21b2, ab product of a and b (Note: We rarely use the notation a ϫ b a times b because the symbol, ϫ, might be a multiplied by b confused with the variable, x.) Division a quotient of a and b a Ϭ b, , aրb, b ͤa a divided by b b b divided into a ratio of a and b a over b a per b
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 62 BA CONFIRMING PAGES 62 Chapter 1 The Set of Real Numbers 2. Evaluating Algebraic Expressions The value of an algebraic expression depends on the values of the variables within the expression. Example 1 Evaluating an Algebraic Expression Evaluate the algebraic expression when p ϭ 4 and q ϭ 3. 4 a. 100 Ϫ p b. pq Solution: a. 100 Ϫ p 100 Ϫ 1 2 When substituting a number for a variable, use parentheses. ϭ 100 Ϫ 142 Substitute p ϭ 4 in the parentheses. ϭ 96 Subtract. b. pq ϭ1 21 2 When substituting a number for a variable, use parentheses. ϭ 142 a b 3 Substitute p ϭ 4 and q ϭ 3. 4 4 4 3 ϭ ؒ Write the whole number as a fraction. 1 4 12 ϭ Multiply fractions. 4 ϭ3 Reduce to lowest terms. Skill Practice Evaluate the algebraic expressions when x ϭ 5 and y ϭ 2. 1a. xy b. 20 Ϫ y 3. Exponential Expressions In algebra, repeated multiplication can be expressed using exponents. The expression 4 ؒ 4 ؒ 4 can be written as exponent 43 base In the expression 43, 4 is the base, and 3 is the exponent, or power. The exponent indicates how many factors of the base to multiply. Skill Practice Answers 1a. 10 b. 18
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 63 BA CONFIRMING PAGES Section 1.2 Order of Operations 63 Definition of b n Let b represent any real number and n represent a positive integer. Then, bn ϭ b ؒ b ؒ b ؒ b p ؒ b ⎧ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎩ n factors of b n b is read as “b to the nth power.” b is called the base, and n is called the exponent, or power. b2 is read as “b squared,” and b3 is read as “b cubed.” The exponent, n, is a count of the number of times the base, b, is used as a factor. Example 2 Evaluating Exponential Expressions Translate the expression into words and then evaluate the expression. 3 3 a. 25 b. 52 c. a b d. 16 4 Solution: a. The expression 25 is read as “two to the fifth power” 25 ϭ 122122122122122 ϭ 32. b. The expression 52 is read as “five to the second power” or “five, squared” 52 ϭ 152152 ϭ 25. c. The expression 1 3 2 3 is read as “three-fourths to the third power” or 4 “three-fourths, cubed” 3 3 a b ϭ a ba ba b ϭ 3 3 3 27 4 4 4 4 64 d. The expression 16 is read as “one to the sixth power” 16 ϭ 112112112112112112 ϭ 1. Skill Practice Evaluate. 2 2 2. 43 3. 24 4. a b 5. 112 7 3 squared equals 9?” The symbol, 1 (called a radical sign), is used to find the 4. Square Roots number is nonnegative. Therefore, 19 is the nonnegative number that when The inverse operation to squaring a number is to find its square roots. For ex- squared equals 9. Hence 19 ϭ 3 because 3 is nonnegative and 132 2 ϭ 9. Several ample, finding a square root of 9 is equivalent to asking “what number(s) when principal square root of a number. By definition, the principal square root of a 164 ϭ 8 1121 ϭ 11 more examples follow: 10 ϭ 0 Because 182 2 ϭ 64 Because 1112 2 ϭ 121 Skill Practice Answers Because 102 2 ϭ 0 2. 64 3. 16 4 4. 5. 1 9
• miL28711_ch01_049-120 9/20/06 02:46 PM Page 64 BA CONFIRMING PAGES B 16 64 Chapter 1 The Set of Real Numbers B9 1 1 1 1 1 ϭ Because ؒ ϭ 4 4 4 16 4 2 2 2 4 ϭ Because ؒ ϭ 3 3 3 9 10 ϭ 0 149 ϭ 7 11 ϭ 1 164 ϭ 8 TIP: To simplify square roots, it is advisable to become familiar with the following squares and square roots. 14 ϭ 2 181 ϭ 9 02 ϭ 0 72 ϭ 49 19 ϭ 3 1100 ϭ 10 1 ϭ1 2 8 ϭ 64 2 116 ϭ 4 1121 ϭ 11 2 ϭ4 2 9 ϭ 81 2 125 ϭ 5 1144 ϭ 12 3 ϭ9 2 10 ϭ 100 2 136 ϭ 6 1169 ϭ 13 4 ϭ 16 2 11 ϭ 121 2 5 ϭ 25 2 12 ϭ 144 2 6 ϭ 36 2 13 ϭ 169 2 5. Order of Operations When algebraic expressions contain numerous operations, it is important to evaluate the operations in the proper order. Parentheses 1 2, brackets 3 4, and braces 5 6 are used for grouping numbers and algebraic expressions. It is im- portant to recognize that operations within parentheses and other grouping symbols must be done first. Other grouping symbols include absolute value bars, radical signs, and fraction bars. Order of Operations 1. Simplify expressions within parentheses and other grouping symbols first. These include absolute value bars, fraction bars, and radicals. If imbedded parentheses are present, start with the innermost parentheses. 2. Evaluate expressions involving exponents and radicals. 3. Perform multiplication or division in the order that they occur from left to right. 4. Perform addition or subtraction in the order that they occur from left to right. Example 3 Applying the Order of Operations d. 6.2 Ϫ 0 Ϫ2.1 0 ϩ 115 Ϫ 6 Simplify the expressions. a Ϫ b 1 5 3 a. 17 Ϫ 3 ؒ 2 ϩ 22 b. 2 6 4 c. 25 Ϫ 12 Ϭ 3 ؒ 4 e. 28 Ϫ 23 16 Ϫ 32 2 ϩ 44
• miL28711_ch01_049-120 9/20/06 11:34 AM Page 65 BA CONFIRMING PAGES Section 1.2 Order of Operations 65 Solution: a. 17 Ϫ 3 ؒ 2 ϩ 22 ϭ 17 Ϫ 3 ؒ 2 ϩ 4 Simplify exponents. ϭ 17 Ϫ 6 ϩ 4 Multiply before adding or subtracting. ϭ 11 ϩ 4 Add or subtract from left to right. ϭ 15 a Ϫ b 1 5 3 b. Subtract fractions within the parentheses. 2 6 4 a Ϫ b 1 10 9 ϭ The least common denominator is 12. 2 12 12 a b 1 1 ϭ 2 12 1 ϭ Multiply fractions. 24 c. 25 Ϫ 12 Ϭ 3 ؒ 4 Multiply or divide in order from left to right. ϭ 25 Ϫ 4 ؒ 4 Notice that the operation 12 Ϭ 3 is performed first (not 3 ؒ 4). ϭ 25 Ϫ 16 Multiply 4 ؒ 4 before subtracting. d. 6.2 Ϫ 0Ϫ2.1 0 ϩ 115 Ϫ 6 ϭ9 ϭ 6.2 Ϫ 0Ϫ2.1 0 ϩ 19 Subtract. Simplify within the square root. ϭ 6.2 Ϫ 12.12 ϩ 3 Simplify the square root and absolute value. ϭ 4.1 ϩ 3 Add or subtract from left to right. ϭ 7.1 Add. e. 28 Ϫ 23 16 Ϫ 32 2 ϩ 44 ϭ 28 Ϫ 23 132 2 ϩ 44 Simplify within the inner parentheses first. ϭ 28 Ϫ 2 3 192 ϩ 44 Simplify exponents. ϭ 28 Ϫ 23134 Add within the square brackets. ϭ 28 Ϫ 26 Multiply before subtracting. ϭ2 Subtract. Skill Practice Simplify the expressions. Ϫ 110 Ϫ 22 13 1 6. 14 Ϫ 3 ؒ 2 7. 8. 1 ϩ 2 ؒ 32 Ϭ 6 4 4 9. ƒϪ20 ƒ Ϫ 17 Ϫ 22 10. 60 Ϫ 53 16 Ϫ 32 ϩ 22 4 Skill Practice Answers 5 6. 8 7. 8. 4 4 9. 15 10. 25
• miL28711_ch01_049-120 9/20/06 11:35 AM Page 66 BA CONFIRMING PAGES 66 Chapter 1 The Set of Real Numbers 6. Translations Example 4 Translating from English Form to Algebraic Form Translate each English phrase to an algebraic expression. a. The quotient of x and 5 b. The difference of p and the square root of q c. Seven less than n d. Seven less n e. Eight more than the absolute value of w b. p Ϫ 1q Solution: x a. or xϬ5 The quotient of x and 5 5 The difference of p and the square root of q c. n Ϫ 7 Seven less than n Avoiding Mistakes: d. 7 Ϫ n Seven less n Recall that “a less than b” is translated as b Ϫ a. Therefore, e. 0w 0 ϩ 8 Eight more than the absolute value of w the statement “seven less than n” must be translated as n Ϫ 7, Skill Practice Translate each English phrase to an algebraic expression. not 7 Ϫ n. 11. The product of 6 and y 12. The sum of b and the square root of c 13. Twelve less than x 14. Twelve less x 15. One more than two times x Example 5 Translating from English Form to Algebraic Form Translate each English phrase into an algebraic expression. Then evaluate the expression for a ϭ 6, b ϭ 4, and c ϭ 20. a. The product of a and the square root of b b. Twice the sum of b and c c. The difference of twice a and b 2 11 Solution: ϭ 162 1142 a. a1b The product of a and the square root of b. ϭ1 2 Use parentheses to substitute a number for a variable. Substitute a ϭ 6 and b ϭ 4. ϭ6ؒ2 Simplify the radical first. ϭ 12 Multiply. 12. b ϩ 1c Skill Practice Answers 11. 6y 13. x Ϫ 12 14. 12 Ϫ x 15. 2x ϩ 1
• miL28711_ch01_049-120 9/20/06 11:35 AM Page 67 BA CONFIRMING PAGES Section 1.2 Order of Operations 67 b. 21b ϩ c2 Twice the sum of b and c. To compute “twice the sum of b and c,” it is necessary to take the sum first and then multiply by 2. To ensure the proper order, the sum of b and c must be enclosed in parentheses. The proper translation is 21b ϩ c2 . ϭ 211 2ϩ1 22 Use parentheses to substitute a number for a variable. ϭ 21142 ϩ 12022 Substitute b ϭ 4 and c ϭ 20. ϭ 21242 Simplify within the parentheses first. ϭ 48 Multiply. c. 2a Ϫ b The difference of twice a and b. ϭ 21 2Ϫ1 2 Use parentheses to substitute a number for a variable. ϭ 2162 Ϫ 142 Substitute a ϭ 6 and b ϭ 4. ϭ 12 Ϫ 4 Multiply first. ϭ8 Subtract. Skill Practice Translate each English phrase to an algebraic expression. Then evaluate the expression for x ϭ 3, y ϭ 9, z ϭ 10. 16. The quotient of the square root of y and x 17. One-half the sum of x and y 18. The difference of z and twice x Calculator Connections On a calculator, we enter exponents higher than the second power by using the key labeled yx or ٙ . For example, evaluate 24 and 106: Scientific Calculator Enter: 2 yx 4 ϭ Result: 16 Enter: 10 yx 6 ϭ Result: 1000000 Graphing Calculator Most calculators also have the capability to enter several operations at once. c. 125 Ϫ 9 However, it is important to note that fraction bars and radicals require user- 1y defined parentheses to ensure that the proper order of operations is fol- lowed. For example, evaluate the following expressions on a calculator: 18 Ϫ 2 Skill Practice Answers a. 130 Ϫ 215 Ϫ 12 3 b. 11 Ϫ 9 1x ϩ y2; 6 1 16. ;1 17. x 2 18. z Ϫ 2x ; 4
• miL28711_ch01_049-120 9/20/06 11:35 AM Page 68 BA CONFIRMING PAGES 68 Chapter 1 The Set of Real Numbers Scientific Calculator ) 1 Enter: 130 Ϫ 2 ϫ ( 5 Ϫ 1 ) yx 3 ϭ Result: 2 Enter: ( 18 Ϫ 2 ) Ϭ ( 11 Ϫ 9 ) ϭ Result: 8 Enter: ( 25 Ϫ 9 Result: 4 Graphing Calculator Calculator Exercises Simplify the expressions without the use of a calculator. Then enter the expressions into the calculator to verify your answers. 6. 3 ؒ 8 Ϫ 232 ϩ 22 4ϩ6 1. 2. 110 Ϫ 512 ϩ 12 Ϫ 4 3. 100 Ϫ 215 Ϫ 32 3 7. 118 Ϫ 2 8Ϫ3 4. 3 ϩ 14 Ϫ 12 2 5. 112 Ϫ 6 ϩ 12 2 20 Ϫ 32 8. 14 ؒ 3 Ϫ 3 ؒ 32 3 9. 26 Ϫ 22 Section 1.2 Practice Exercises Boost your GRADE at • Practice Problems • e-Professors mathzone.com! • Self-Tests • Videos • NetTutor Study Skills Exercises 1. Sometimes you may run into a problem with homework or you find that you are having trouble keeping up with the pace of the class. A tutor can be a good resource. Answer the following questions. a. Does your college offer tutoring? b. Is it free? c. Where would you go to sign up for a tutor? 2. Define the key terms: a. variable b. constant c. expression d. base e. exponent f. square root g. order of operations e Ϫ4, 5.6, 129, 0, p, 4.02, f Review Exercises 7 3. Which of the following are rational numbers. 9 4. Evaluate. 0 Ϫ56 0 5. Evaluate. 0 9.2 0 6. Find the opposite of 19. 7. Find the opposite of Ϫ34.2.
• miL28711_ch01_049-120 9/20/06 02:31 PM Page 69 BA CONFIRMING PAGES Section 1.2 Order of Operations 69 Concept 2: Evaluating Algebraic Expressions For Exercises 8–19, evaluate the expressions for the given substitutions. 15 8. y Ϫ 3 when y ϭ 18 9. 3q when q ϭ 5 10. when t ϭ 5 t 2 6 11. 8 ϩ w when w ϭ 12 12. 5 ϩ 6d when d ϭ 13. hϪ1 when h ϭ 10 3 5 3 2 2 14. 21c ϩ 12 Ϫ 5 when c ϭ 4 15. 414x Ϫ 12 when x ϭ 16. p2 ϩ when p ϭ 4 9 3 2 2 17. z3 Ϫ when z ϭ 18. 51x ϩ 2.32 when x ϭ 1.1 19. 312.1 Ϫ y2 when y ϭ 0.5 27 3 20. The area of a rectangle may be computed as A ϭ /w, where / is the length of the rectangle and w is the width. Find the area for the rectangle shown. 160 ft 21. The perimeter of the rectangle from Exercise 20 may be computed as 360 ft P ϭ 2/ ϩ 2w. Find the perimeter. b2 ϭ 6 ft 22. The area of a trapezoid is given by A ϭ 1 1b1 ϩ b2 2h, where b1 and b2 are the lengths 2 of the two parallel sides and h is the height. Find the area of the trapezoid with h ϭ 3 ft dimensions shown in the figure. b1 ϭ 8 ft 23. The volume of a rectangular solid is given by V ϭ /wh, where / is the length of the box, w is the width, and h is the height. Find the volume of 2 yd the box shown in the figure. 20 yd Concept 3: Exponential Expressions 25 yd For Exercises 24–31, write each of the products using exponents. 1 1 1 1 24. ؒ ؒ ؒ 25. 10 ؒ 10 ؒ 10 ؒ 10 ؒ 10 ؒ 10 26. a ؒ a ؒ a ؒ b ؒ b 6 6 6 6 27. 7 ؒ x ؒ x ؒ y ؒ y 28. 5c ؒ 5c ؒ 5c ؒ 5c ؒ 5c 29. 3 ؒ w ؒ z ؒ z ؒ z ؒ z 2 2 2 30. 8 ؒ y ؒ x ؒ x ؒ x ؒ x ؒ x ؒ x 31. tؒ tؒ t 3 3 3 32. a. For the expression 5x3, what is the base for the exponent 3? b. Does 5 have an exponent? If so, what is it? 33. a. For the expression 2y4, what is the base for the exponent 4? b. Does 2 have an exponent? If so, what is it? For Exercises 34–41, write each expression in expanded form using the definition of an exponent. 34. x3 35. y4 36. 12b2 3 37. 18c2 2 38. 10y5 39. x2y3 40. 2wz2 41. 3a3b
• miL28711_ch01_049-120 9/20/06 11:35 AM Page 70 BA CONFIRMING PAGES 70 Chapter 1 The Set of Real Numbers For Exercises 42–49, simplify the expressions. 1 2 1 5 42. 52 43. 43 44. a b 45. a b 7 2 46. 10.252 3 47. 10.82 2 48. 26 49. 132 50. 181 51. 164 52. 14 53. 19 Concept 4: Square Roots 54. 1100 55. 149 56. 116 57. 136 For Exercises 50–61, simplify the square roots. A9 A 64 A 81 A 100 1 1 25 49 58. 59. 60. 61. Concept 5: Order of Operations For Exercises 62–89, use the order of operations to simplify the expressions. 62. 8 ϩ 2 ؒ 6 63. 7 ϩ 3 ؒ 4 64. 18 ϩ 226 65. 17 ϩ 324 1 2 1 3 2 2 66. 4 ϩ 2 Ϭ 2 ؒ 3 ϩ 1 67. 5 ϩ 6 ؒ 2 Ϭ 4 Ϫ 1 68. ؒ Ϫ 69. ؒ ϩ 4 3 6 4 3 3 9 1 3 11 3 4 70. Ϫ ؒ 71. Ϫ ؒ 72. 33 5 ϩ 218 Ϫ 32 4 73. 23 4 ϩ 316 Ϫ 42 4 78. 22 ϩ 19 ؒ 5 79. 32 ϩ 116 ؒ 2 80. 19 ϩ 16 Ϫ 2 81. 136 ϩ 13 Ϫ 5 8 3 4 6 8 3 74. 10 ϩ 0Ϫ6 0 75. 18 ϩ 0Ϫ3 0 76. 21 Ϫ 0 8 Ϫ 2 0 77. 12 Ϫ 0 6 Ϫ 1 0 87. 118 Ϭ 14 2 ؒ 5 3 192 Ϫ 12 Ϭ 24 Ϫ 156 7 ϩ 318 Ϫ 22 16 Ϫ 8 Ϭ 4 15 Ϫ 513 ؒ 2 Ϫ 42 517 Ϫ 32 ϩ 816 Ϫ 42 17 ϩ 3218 Ϫ 22 437 ϩ 312 ؒ 9 Ϫ 82 4 82. 83. 84. 85. 4ϩ8Ϭ4Ϫ2 10 Ϫ 214 ؒ 5 Ϫ 162 86. 3 42 ؒ 16 Ϫ 42 Ϭ 8 4 ϩ 37 ؒ 18 Ϫ 32 4 88. 48 Ϫ 13 ؒ 3 ϩ 3 150 Ϫ 7 ؒ 52 ϩ 24 89. 80 Ϭ 16 ؒ 2 ϩ 162 Ϫ 0 Ϫ2 0 2 Concept 6: Translations For Exercises 90–101, translate each English phrase into an algebraic expression. 90. The product of 3 and x 91. The sum of b and 6 92. The quotient of x and 7 93. Four divided by k 94. The difference of 2 and a 95. Three subtracted from t 96. x more than twice y 97. Nine decreased by the product of 3 and p 98. Four times the sum of x and 12 99. Twice the difference of x and 3 100. Q less than 3 101. Fourteen less than t
• miL28711_ch01_049-120 9/20/06 11:36 AM Page 74 BA CONFIRMING PAGES 74 Chapter 1 The Set of Real Numbers d. Ϫ ϩ aϪ b 4 6 The least common denominator (LCD) is 21. 3 7 4ؒ7 6ؒ3 ϭϪ ϩ aϪ b Write each fraction with the LCD. 3ؒ7 7ؒ3 ϩ aϪ b 28 18 ϭϪ Find the absolute value of the addends. 21 21 `Ϫ ` ϭ and ` Ϫ ` ϭ 28 28 18 18 . 21 21 21 21 ϩ b 28 18 ϭ Ϫa Add their absolute values and apply the common 21 21 sign (in this case, the common sign is negative). common sign is negative 46 46 ϭϪ The sum is Ϫ . 21 21 Skill Practice Add the numbers. 4. Ϫ5 ϩ 1Ϫ252 5. 7 ϩ 12 6. Ϫ14.8 ϩ 1Ϫ9.72 7. Ϫ ϩ aϪ b 1 5 2 8 Example 3 Adding Real Numbers with Different Signs Add. a. 12 ϩ 1Ϫ172 ϩ aϪ b 2 4 b. Ϫ10.6 ϩ 20.4 c. Ϫ8 ϩ 8 d. 15 5 Solution: a. 12 ϩ 1Ϫ172 First find the absolute value of the addends. 0 12 0 ϭ 12 and 0 Ϫ17 0 ϭ 17. The absolute value of Ϫ17 is greater than the absolute value of 12. Therefore, the sum is negative. ϭ Ϫ117 Ϫ 122 Next, subtract the smaller absolute value from the larger absolute value. Apply the sign of the number with the larger absolute value. ϭ Ϫ5 b. Ϫ10.6 ϩ 20.4 First find the absolute value of the addends. 0 Ϫ10.6 0 ϭ 10.6 and 0 20.4 0 ϭ 20.4. The absolute value of 20.4 is greater than the absolute value of Ϫ10.6. Therefore, the sum is positive. ϭ ϩ120.4 Ϫ 10.62 Next, subtract the smaller absolute value from Skill Practice Answers the larger absolute value. 4. Ϫ30 5. 19 Apply the sign of the number with the larger absolute value. 9 6. Ϫ24.5 7. Ϫ ϭ 9.8 8
• miL28711_ch01_049-120 9/20/06 11:36 AM Page 75 BA CONFIRMING PAGES Section 1.3 Addition of Real Numbers 75 c. Ϫ8 ϩ 8 First find the absolute value of the addends. 0 Ϫ8 0 ϭ 8 and 0 8 0 ϭ 8. ϭ 18 Ϫ 82 The absolute values are equal. Therefore, their difference is 0. The number zero is neither positive ϭ0 nor negative. ϩ aϪ b 2 4 d. The least common denominator is 15. 15 5 4ؒ3 ϩ aϪ b 2 ϭ Write each fraction with the LCD. 15 5ؒ3 ϩ aϪ b 2 12 ϭ Find the absolute value of the addends. 15 15 ` ` ϭ `Ϫ ` ϭ 2 2 12 12 and 15 15 15 15 The absolute value of Ϫ12 is greater than the 15 2 absolute value of 15. Therefore, the sum is negative. Ϫ b 12 2 ϭ Ϫa Next, subtract the smaller absolute value from the 15 15 larger absolute value. Apply the sign of the number with the larger absolute value. 10 ϭϪ Subtract. 15 2 2 10 2 ϭϪ Simplify by reducing to lowest terms. Ϫ ϭ Ϫ 3 15 3 3 Skill Practice Add the numbers. 8. Ϫ15 ϩ 16 9. 27.3 ϩ 1Ϫ18.12 10. 6.2 ϩ 1Ϫ6.22 9 2 11. Ϫ ϩ 10 5 3. Translations Example 4 Translating Expressions Involving the Addition of Real Numbers Translate each English phrase into an algebraic expression. Then simplify the result. a. The sum of Ϫ12, Ϫ8, 9, and Ϫ1 b. Negative three-tenths added to Ϫ7 8 c. The sum of Ϫ12 and its opposite Solution: a. Ϫ12 ϩ 1Ϫ82 ϩ 9 ϩ 1Ϫ12 The sum of Ϫ12, Ϫ8, 9, and Ϫ1. ϭ Ϫ20 ϩ 9 ϩ 1Ϫ12 ⎧ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎩ Add from left to right. Skill Practice Answers Ϫ11 ϩ 1Ϫ12 ⎧ ⎪ ⎪ ⎨ ⎪ ⎪ ⎩ ϭ 8. 1 9. 9.2 ⎧ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎩ 1 ϭ Ϫ12 10. 0 11. Ϫ 2
• miL28711_ch01_049-120 9/20/06 11:36 AM Page 76 BA CONFIRMING PAGES 76 Chapter 1 The Set of Real Numbers b. Ϫ ϩ aϪ b 7 3 Negative three-tenths added to Ϫ7. 8 8 10 ϩ aϪ b 35 12 ϭϪ Get a common denominator. 40 40 47 ϭϪ The numbers have the same signs. Add their 40 absolute values and keep the common sign. Ϫ Q35 ϩ 12 R . 40 40 TIP: The sum of any number and its opposite c. Ϫ12 ϩ 1122 The sum of Ϫ12 and its opposite. is 0. ϭ0 Add. Skill Practice Translate to an algebraic expression, and simplify the result. 9 11 12. The sum of Ϫ10, 4, and Ϫ6 13. The sum of Ϫ and 4 3 14. Ϫ60 added to its opposite 4. Applications Involving Addition of Real Numbers Example 5 Adding Real Numbers in Applications a. A running back on a football team gains 4 yards (yd). On the next play, the quarterback is sacked and loses 13 yd. Write a mathematical expression to describe this situation and then simplify the result. b. A student has \$120 in her checking account. After depositing her paycheck of \$215, she writes a check for \$255 to cover her portion of the rent and another check for \$294 to cover her car payment. Write a mathematical expression to describe this situation and then simplify the result. Solution: a. 4 ϩ 1Ϫ132 The loss of 13 yd can be interpreted as adding Ϫ13 yd. ϭ Ϫ9 The football team has a net loss of 9 yd. b. 120 ϩ 215 ϩ 1Ϫ2552 ϩ 1Ϫ2942 Writing a check is equivalent to adding ⎧ ⎪ ⎪ ⎨ ⎪ ⎪ ⎩ a negative amount to the bank account. ϭ 335 ϩ 1Ϫ2552 ϩ 1Ϫ2942 Use the order of operations. Add from ⎧ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎩ left to right. ϭ 80 ϩ 1Ϫ2942 ϭ Ϫ214 The student has overdrawn her account by \$214. Skill Practice Skill Practice Answers 15. A share of GE stock was priced at \$32.00 per share at the beginning of the 12. Ϫ10 ϩ 4 ϩ 1Ϫ62; Ϫ12 month. After the first week, the price went up \$2.15 per share. At the end 9 11 17 13. Ϫ ϩ ; of the second week it went down \$3.28 per share. Write a mathematical 4 3 12 14. 60 ϩ 1Ϫ602; 0 expression to describe the price of the stock and find the price of the stock 15. 32.00 ϩ 2.15 ϩ (Ϫ3.28); at the end of the 2-week period. \$30.87 per share
• miL28711_ch01_049-120 9/20/06 11:36 AM Page 77 BA CONFIRMING PAGES Section 1.3 Addition of Real Numbers 77 Section 1.3 Practice Exercises Boost your GRADE at • Practice Problems • e-Professors mathzone.com! • Self-Tests • Videos • NetTutor Study Skills Exercise 1. It is very important to attend class every day. Math is cumulative in nature, and you must master the material learned in the previous class to understand today’s lesson. Because this is so important, many instructors tie attendance to the final grade. Write down the attendance policy for your class. Review Exercises Plot the points in set A on a number line. Then for Exercises 2–7 place the appropriate inequality (<, >) between the expressions. A ϭ e Ϫ2, , Ϫ , 3, , 1.6, 0 f 3 5 9 4 2 2 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 9 _____ 3 5 2. Ϫ2 _____ 0 3. 4. Ϫ2 _____ Ϫ 2 4 2 5 3 _____ 3 _____ 5 5. 0 _____ Ϫ 6. 1.6 7. Ϫ 2 4 4 2 Concept 1: Addition of Real Numbers and the Number Line For Exercises 8–15, add the numbers using the number line. Ϫ8 Ϫ7 Ϫ6 Ϫ5 Ϫ4 Ϫ3 Ϫ2 Ϫ1 0 1 2 3 4 5 6 7 8 8. Ϫ2 ϩ 1Ϫ42 9. Ϫ3 ϩ 1Ϫ52 10. Ϫ7 ϩ 10 11. Ϫ2 ϩ 9 12. 6 ϩ 1Ϫ32 13. 8 ϩ 1Ϫ22 14. 2 ϩ 1Ϫ52 15. 7 ϩ 1Ϫ32 Concept 2: Addition of Real Numbers For Exercises 16–43, add the integers. 16. Ϫ19 ϩ 2 17. Ϫ25 ϩ 18 18. Ϫ4 ϩ 11 19. Ϫ3 ϩ 9 20. Ϫ16 ϩ 1Ϫ32 21. Ϫ12 ϩ 1Ϫ232 22. Ϫ2 ϩ 1Ϫ212 23. Ϫ13 ϩ 1Ϫ12 24. 0 ϩ 1Ϫ52 25. 0 ϩ 1Ϫ42 26. Ϫ3 ϩ 0 27. Ϫ8 ϩ 0 28. Ϫ16 ϩ 16 29. 11 ϩ 1Ϫ112 30. 41 ϩ 1Ϫ412 31. Ϫ15 ϩ 15 32. 4 ϩ 1Ϫ92 33. 6 ϩ 1Ϫ92 34. 7 ϩ 1Ϫ22 ϩ 1Ϫ82 35. 2 ϩ 1Ϫ32 ϩ 1Ϫ62 36. Ϫ17 ϩ 1Ϫ32 ϩ 20 37. Ϫ9 ϩ 1Ϫ62 ϩ 15 38. Ϫ3 ϩ 1Ϫ82 ϩ 1Ϫ122 39. Ϫ8 ϩ 1Ϫ22 ϩ 1Ϫ132
• miL28711_ch01_049-120 9/20/06 11:36 AM Page 78 BA CONFIRMING PAGES 78 Chapter 1 The Set of Real Numbers 40. Ϫ42 ϩ 1Ϫ32 ϩ 45 ϩ 1Ϫ62 41. 36 ϩ 1Ϫ32 ϩ 1Ϫ82 ϩ 1Ϫ252 42. Ϫ5 ϩ 1Ϫ32 ϩ 1Ϫ72 ϩ 4 ϩ 8 43. Ϫ13 ϩ 1Ϫ12 ϩ 5 ϩ 2 ϩ 1Ϫ202 For Exercises 44–69, add the rational numbers. 44. 23.81 ϩ 1Ϫ2.512 2 1 1 5 45. Ϫ9.23 ϩ 10.53 46. Ϫ ϩ 47. Ϫ ϩ 7 14 8 16 ϩ aϪ b ϩ aϪ b 50. Ϫ ϩ aϪ b 51. Ϫ ϩ aϪ b 2 5 1 3 7 1 1 4 48. 49. 3 6 2 4 8 16 9 3 54. Ϫ2.1 ϩ aϪ b 55. Ϫ8.3 ϩ aϪ b 1 3 7 7 3 9 52. Ϫ ϩ 53. Ϫ ϩ 4 10 6 8 10 10 ϩ 1Ϫ0.52 58. 8.23 ϩ 1Ϫ8.232 3 3 56. 57. Ϫ ϩ 0.45 59. Ϫ7.5 ϩ 7.5 4 2 61. 0 ϩ aϪ b 62. Ϫ ϩ aϪ b ϩ 2 63. Ϫ ϩ aϪ b ϩ 2 7 21 2 1 1 3 60. Ϫ ϩ 0 8 22 3 9 4 2 64. Ϫ47.36 ϩ 24.28 65. Ϫ0.015 ϩ 10.00262 66. 516.816 ϩ 1Ϫ22.132 67. 87.02 ϩ 1Ϫ93.192 68. Ϫ0.000617 ϩ 1Ϫ0.00152 69. Ϫ5315.26 ϩ 1Ϫ314.892 70. State the rule for adding two numbers with different signs. 72. x ϩ y ϩ 1z 71. State the rule for adding two numbers with the same signs. For Exercises 72–79, evaluate the expression for x ϭ Ϫ3, y ϭ Ϫ2, and z ϭ 16. 73. 2z ϩ x ϩ y 74. y ϩ 31z 75. Ϫ1z ϩ y 76. 0x 0 ϩ 0 y 0 77. z ϩ x ϩ 0 y 0 78. Ϫx ϩ y 79. x ϩ 1Ϫy2 ϩ z Concept 3: Translations For Exercises 80–89, translate the English phrase into an algebraic expression. Then evaluate the expression. 80. The sum of Ϫ6 and Ϫ10 81. The sum of Ϫ3 and 5 82. Negative three increased by 8 83. Twenty-one increased by 4 84. Seventeen more than Ϫ21 85. Twenty-four more than Ϫ7 86. Three times the sum of Ϫ14 and 20 87. Two times the sum of Ϫ6 and 10 88. Five more than the sum of Ϫ7 and Ϫ2 89. Negative six more than the sum of 4 and Ϫ1 Concept 4: Applications Involving Addition of Real Numbers 90. The temperature in Minneapolis, Minnesota, began at Ϫ5°F (5° below zero) at 6:00 A.M. By noon the temperature had risen 13°, and by the end of the day, the temperature had dropped 11° from its noon time high. Write an expression using addition that describes the changes in temperature during the day. Then evaluate the expression to give the temperature at the end of the day.
• miL28711_ch01_049-120 9/20/06 11:36 AM Page 81 BA CONFIRMING PAGES Section 1.4 Subtraction of Real Numbers 81 Example 2 Subtracting Real Numbers Ϫ aϪ b 3 4 a. b. Ϫ2.3 Ϫ 6.04 20 15 Solution: Ϫ aϪ b 3 4 a. The least common denominator is 60. 20 15 Ϫ aϪ b 9 16 Write equivalent fractions with the LCD. 60 60 ϩa b 9 16 Write in terms of addition. 60 60 25 Add. 60 5 Reduce to lowest terms. 12 b. Ϫ2.3 Ϫ 6.04 Ϫ2.3 ϩ 1Ϫ6.042 Write in terms of addition. Ϫ8.34 Add. Skill Practice Subtract. 6. 7.5 Ϫ 1Ϫ1.52 1 7 5. Ϫ Ϫ 6 12 2. Translations Example 3 Translating Expressions Involving Subtraction Write an algebraic expression for each English phrase and then simplify the result. a. The difference of Ϫ7 and Ϫ5 b. 12.4 subtracted from Ϫ4.7 c. Ϫ24 decreased by the sum of Ϫ10 and 13 d. Seven-fourths less than one-third Solution: a. Ϫ7 Ϫ 1Ϫ52 The difference of Ϫ7 and Ϫ5 ϭ Ϫ7 ϩ 152 Rewrite subtraction in terms of addition. ϭ Ϫ2 Simplify. b. Ϫ4.7 Ϫ 12.4 12.4 subtracted from Ϫ4.7 ϭ Ϫ4.7 ϩ 1Ϫ12.42 Rewrite subtraction in terms of addition. ϭ Ϫ17.1 Simplify. TIP: Recall that “b subtracted from a” is translated as a Ϫ b. In Example 3(b), Skill Practice Answers Ϫ4.7 is written first and then 12.4 is subtracted. 3 5. Ϫ 6. 9 4
• miL28711_ch01_049-120 9/20/06 11:36 AM Page 82 BA CONFIRMING PAGES 82 Chapter 1 The Set of Real Numbers c. Ϫ24 Ϫ 1Ϫ10 ϩ 132 Ϫ24 decreased by the sum of Ϫ10 and 13 ϭ Ϫ24 Ϫ 132 Simplify inside parentheses. ϭ Ϫ24 ϩ 1Ϫ32 Rewrite subtraction in terms of addition. ϭ Ϫ27 Simplify. TIP: Parentheses must be used around the sum of Ϫ10 and 13 so that Ϫ24 is decreased by the entire quantity 1Ϫ10 ϩ 132 . 1 7 d. Ϫ Seven-fourths less than one-third 3 4 ϩ aϪ b 1 7 ϭ Rewrite subtraction in terms of addition. 3 4 ϩ aϪ b 4 21 ϭ The common denominator is 12. 12 12 17 5 ϭϪ or Ϫ1 12 12 Skill Practice Write an algebraic expression for each phrase and then simplify. 7. 8 less than Ϫ10 8. Ϫ72 subtracted from Ϫ82 9. The difference of 2.6 and Ϫ14.7 10. Two-fifths decreased by four-thirds 3. Applications Involving Subtraction Example 4 Using Subtraction of Real Numbers in an Application During one of his turns on Jeopardy, Harold selected the category “Show Tunes.” He got the following results: the \$200 question correct; the \$400 question incor- rect; the \$600 question correct; the \$800 question incorrect; and the \$1000 ques- tion correct. Write an expression that determines Harold’s score. Then simplify the expression to find his total winnings for that category. Solution: 200 Ϫ 400 ϩ 600 Ϫ 800 ϩ 1000 ϭ 200 ϩ 1Ϫ4002 ϩ 600 ϩ 1Ϫ8002 ϩ 1000 Rewrite subtraction in terms of addition. ϭ Ϫ200 ϩ 600 ϩ 1Ϫ8002 ϩ 1000 Add from left to right. ϭ 400 ϩ 1Ϫ8002 ϩ 1000 Skill Practice Answers ϭ Ϫ400 ϩ 1000 7. Ϫ10 Ϫ 8; Ϫ18 8. Ϫ82 Ϫ (Ϫ72); Ϫ10 ϭ 600 Harold won \$600 in that 9. 2.6 Ϫ (Ϫ14.7); 17.3 category. 2 4 14 10. Ϫ ; Ϫ 5 3 15
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 83 BA CONFIRMING PAGES Section 1.4 Subtraction of Real Numbers 83 Skill Practice 11. During Harold’s first round on Jeopardy, he got the \$100, \$200, and \$400 questions correct but he got the \$300 and \$500 questions incorrect. Deter- mine Harold’s score for this round. Example 5 Using Subtraction of Real Numbers in an Application The highest recorded temperature in North America was 134°F, recorded on July 10, 1913, in Death Valley, California. The lowest temperature of Ϫ81°F was recorded on February 3, 1947, in Snag, Yukon, Canada. Find the difference between the highest and lowest recorded temperatures in North America. Solution: 134 Ϫ 1Ϫ812 ϭ 134 ϩ 1812 Rewrite subtraction in terms of addition. ϭ 215 Add. The difference between the highest and lowest temperatures is 215°F. Skill Practice 12. The record high temperature for the state of Montana occurred in 1937 and was 117°F. The record low occurred in 1954 and was Ϫ70°F. Find the difference between the highest and lowest temperatures. 4. Applying the Order of Operations b. 5 Ϫ 135 Ϫ 1Ϫ142 Ϫ 2 Example 6 Applying the Order of Operations Simplify the expressions. a. Ϫ6 ϩ 510 Ϫ 3 7 Ϫ 1Ϫ42 4 6 c. aϪ Ϫ b Ϫ a ϩ 2b d. Ϫ6 Ϫ 07 Ϫ 110 ϩ 1Ϫ3 ϩ 72 2 5 2 1 8 3 8 Solution: a. Ϫ6 ϩ 510 Ϫ 37 Ϫ 1Ϫ42 4 6 Work inside the inner brackets first. ϭ Ϫ6 ϩ 510 Ϫ 37 ϩ 142 4 6 Rewrite subtraction in terms of addition. ϭ Ϫ6 ϩ 510 Ϫ 11126 Simplify the expression inside braces. ϭ Ϫ6 ϩ 510 ϩ 1Ϫ1126 Rewrite subtraction in terms of addition. ϭ Ϫ6 ϩ 1Ϫ12 ϭ Ϫ7 Add. Skill Practice Answers 11. Ϫ100, Harold lost \$100. 12. 187°F
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 85 BA CONFIRMING PAGES Section 1.4 Subtraction of Real Numbers 85 Calculator Connections Most calculators can add, subtract, multiply, and divide signed numbers. It is important to note, however, that the key used for the negative sign is differ- ent from the key used for subtraction. On a scientific calculator, the ϩ/Ϫ key or ϩ‫ی‬Ϫ key is used to enter a negative number or to change the sign ‫ۍ‬ of an existing number. On a graphing calculator, the 1Ϫ2 key is used. These keys should not be confused with the Ϫ key which is used for subtraction. For example, try simplifying the following expressions. a. Ϫ7 ϩ 1Ϫ42 Ϫ 6 b. Ϫ3.1 Ϫ 1Ϫ0.52 ϩ 1.1 Scientific Calculator Enter: 7 ϩրϪ ϩ ( 4 ϩրϪ ) Ϫ 6 ϭ Result: Ϫ17 Enter: 3 . 1 ϩրϪ Ϫ ( 0 . 5 ϩրϪ ) Result: Ϫ1.5 ϩ 1 . 1 ϭ Graphing Calculator Calculator Exercises Simplify the expression without the use of a calculator. Then use the calculator to verify your answer. 1. Ϫ8 ϩ 1Ϫ52 2. 4 ϩ 1Ϫ52 ϩ 1Ϫ12 3. 627 Ϫ 1Ϫ842 4. Ϫ0.06 Ϫ 0.12 5. Ϫ3.2 ϩ 1Ϫ14.52 6. Ϫ472 ϩ 1Ϫ5182 7. Ϫ12 Ϫ 9 ϩ 4 8. 209 Ϫ 108 ϩ 1Ϫ632 Section 1.4 Practice Exercises Boost your GRADE at • Practice Problems • e-Professors mathzone.com! • Self-Tests • Videos • NetTutor Study Skills Exercise 1. Some instructors allow the use of calculators. Does your instructor allow the use of a calculator? If so, what kind? Will you be allowed to use a calculator on tests or just for occasional calculator problems in the text? Helpful Hint: If you are not permitted to use a calculator on tests, it is good to do your homework in the same way, without the calculator.
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 86 BA CONFIRMING PAGES 86 Chapter 1 The Set of Real Numbers Review Exercises For Exercises 2–5, translate each English phrase into an algebraic expression. 2. The square root of 6 3. The square of x 4. Negative seven increased by 10 5. Two more than Ϫb For Exercises 6–9, simplify the expression. 6. 42 Ϫ 6 Ϭ 2 7. 1 ϩ 36 Ϭ 9 ؒ 2 8. 14 Ϫ 0 10 Ϫ 6 0 9. 0 Ϫ12 ϩ 7 0 Concept 1: Subtraction of Real Numbers For Exercises 10–17, fill in the blank to make each statement correct. 10. 5 Ϫ 3 ϭ 5 ϩ ________ 11. 8 Ϫ 7 ϭ 8 ϩ ________ 12. Ϫ2 Ϫ 12 ϭ Ϫ2 ϩ ________ 13. Ϫ4 Ϫ 9 ϭ Ϫ4 ϩ ________ 14. 7 Ϫ 1Ϫ42 ϭ 7 ϩ ________ 15. 13 Ϫ 1Ϫ42 ϭ 13 ϩ ________ 16. Ϫ9 Ϫ 1Ϫ32 ϭ Ϫ9 ϩ ________ 17. Ϫ15 Ϫ 1Ϫ102 ϭ Ϫ15 ϩ ________ For Exercises 18–41, subtract the integers. 18. 3 Ϫ 5 19. 9 Ϫ 12 20. 3 Ϫ 1Ϫ52 21. 9 Ϫ 1Ϫ122 22. Ϫ3 Ϫ 5 23. Ϫ9 Ϫ 12 24. Ϫ3 Ϫ 1Ϫ52 25. Ϫ9 Ϫ 1Ϫ52 26. 23 Ϫ 17 27. 14 Ϫ 2 28. 23 Ϫ 1Ϫ172 29. 14 Ϫ 1Ϫ22 30. Ϫ23 Ϫ 17 31. Ϫ14 Ϫ 2 32. Ϫ23 Ϫ (Ϫ17) 33. Ϫ14 Ϫ (Ϫ2) 34. Ϫ6 Ϫ 14 35. Ϫ9 Ϫ 12 36. Ϫ7 Ϫ 17 37. Ϫ8 Ϫ 21 38. 13 Ϫ (Ϫ12) 39. 20 Ϫ (Ϫ5) 40. Ϫ14 Ϫ (Ϫ9) 41. Ϫ21 Ϫ (Ϫ17) For Exercises 42–63, subtract the real numbers. Ϫ aϪ b Ϫ aϪ b 6 3 2 5 3 4 7 5 42. Ϫ Ϫ 43. Ϫ Ϫ 44. 45. 5 10 9 3 8 3 10 6 Ϫ aϪ b 49. Ϫ Ϫ aϪ b 1 1 2 3 11 1 7 1 46. Ϫ 47. Ϫ 48. Ϫ 2 10 7 14 12 4 8 6 50. 6.8 Ϫ (Ϫ2.4) 51. 7.2 Ϫ (Ϫ1.9) 52. 3.1 Ϫ 8.82 53. 1.8 Ϫ 9.59 54. Ϫ4 Ϫ 3 Ϫ 2 Ϫ 1 55. Ϫ10 Ϫ 9 Ϫ 8 Ϫ 7 56. 6 Ϫ 8 Ϫ 2 Ϫ 10 57. 20 Ϫ 50 Ϫ 10 Ϫ 5 58. Ϫ36.75 Ϫ 14.25 59. Ϫ84.21 Ϫ 112.16 60. Ϫ112.846 ϩ (Ϫ13.03) Ϫ 47.312 61. Ϫ96.473 ϩ (Ϫ36.02) Ϫ 16.617 62. 0.085 Ϫ (Ϫ3.14) + (0.018) 63. 0.00061 Ϫ (Ϫ0.00057) ϩ (0.0014)
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 87 BA CONFIRMING PAGES Section 1.4 Subtraction of Real Numbers 87 Concept 2: Translations For Exercises 64–73, translate each English phrase into an algebraic expression. Then evaluate the expression. 64. Six minus Ϫ7 65. Eighteen minus Ϫ1 66. Eighteen subtracted from 3 67. Twenty-one subtracted from 8 68. The difference of Ϫ5 and Ϫ11 69. The difference of Ϫ2 and Ϫ18 70. Negative thirteen subtracted from Ϫ1 71. Negative thirty-one subtracted from Ϫ19 72. Twenty less than Ϫ32 73. Seven less than Ϫ3 Concept 3: Applications Involving Subtraction 74. On the game, Jeopardy, Jasper selected the category “The Last.” He got the first four questions correct (worth \$200, \$400, \$600, and \$800) but then missed the last question (worth \$1000). Write an expression that determines Jasper’s score. Then simplify the expression to find his total winnings for that category. 75. On Ethyl’s turn in Jeopardy, she chose the category “Birds of a Feather.” She already had \$1200 when she selected a Double Jeopardy question. She wagered \$500 but guessed incorrectly (therefore she lost \$500). On her next turn, she got the \$800 question correct. Write an expression that determines Ethyl’s score. Then simplify the expression to find her total winnings. 76. In Ohio, the highest temperature ever recorded was 113°F and the lowest was Ϫ39°F. Find the difference between the highest and lowest temperatures. (Source: Information Please Almanac) 77. In Mississippi, the highest temperature ever recorded was 115°F and the lowest was Ϫ19°F. Find the difference between the highest and lowest temperatures. (Source: Information Please Almanac) 78. The highest mountain in the world is Mt. Everest, located in the Himalayas. Its height is 8848 meters (m) (29,028 ft). The lowest recorded depth in the ocean is located in the Marianas Trench in the Pacific Ocean. Its “height” relative to sea level is Ϫ11,033 m (Ϫ36,198 ft). Determine the difference in elevation, in meters, between the highest mountain in the world and the deepest ocean trench. (Source: Information Please Almanac) 79. The lowest point in North America is located in Death Valley, California, at an elevation of Ϫ282 ft (Ϫ86 m). The highest point in North America is Mt. McKinley, Alaska, at an elevation of 20,320 ft (6194 m). Find the difference in elevation, in feet, between the highest and lowest points in North America. (Source: Information Please Almanac) Concept 4: Applying the Order of Operations For Exercises 80–93, perform the indicated operations. Remember to perform addition or subtraction as they occur from left to right. 80. 6 ϩ 8 Ϫ (Ϫ2) Ϫ 4 ϩ 1 81. Ϫ3 Ϫ (Ϫ4) ϩ 1 Ϫ 2 Ϫ 5 82. Ϫ1 Ϫ 7 ϩ (Ϫ3) Ϫ 8 ϩ 10 83. 13 Ϫ 7 ϩ 4 Ϫ 3 Ϫ (Ϫ1) 84. 2 Ϫ (Ϫ8) ϩ 7 ϩ 3 Ϫ 15 85. 8 Ϫ (Ϫ13) ϩ 1 Ϫ 9 86. Ϫ6 ϩ (Ϫ1) ϩ (Ϫ8) ϩ (Ϫ10) 87. Ϫ8 ϩ (Ϫ3) ϩ (Ϫ5) ϩ (Ϫ2) 88. Ϫ6 Ϫ 1 Ϫ 8 Ϫ 10
• miL28711_ch01_049-120 11:15:2006 07:59 Page 88 BA CONFIRMING PAGES 88 Chapter 1 The Set of Real Numbers Ϫ aϪ b Ϫ aϪ b Ϫ 13 8 2 11 9 3 89. Ϫ8 Ϫ 3 Ϫ 5 Ϫ 2 90. Ϫ ϩ 91. 10 15 5 14 7 2 ϩ Ϫ Ϫ aϪ b 93. Ϫ Ϫ Ϫ aϪ b ϩ 2 5 4 1 9 1 5 1 92. 3 9 3 6 8 4 6 8 For Exercises 94–101, evaluate the expressions for a ϭ Ϫ2, b ϭ Ϫ6, and c ϭ Ϫ1. 94. (a ϩ b) Ϫ c 95. (a Ϫ b) ϩ c 96. a Ϫ (b ϩ c) 97. a ϩ (b Ϫ c) 98. (a Ϫ b) Ϫ c 99. (a ϩ b) ϩ c 100. a Ϫ (b Ϫ c) 101. a ϩ (b ϩ c) 102. 129 ϩ 1Ϫ42 Ϫ 7 103. 8 Ϫ 198 ϩ 1Ϫ32 ϩ 5 For Exercises 102–107, evaluate the expression using the order of operations. 104. 010 ϩ 1Ϫ32 0 Ϫ 0 Ϫ12 ϩ 1Ϫ62 0 3Ϫ4ϩ5 12 Ϫ 14 ϩ 6 105. 0 6 Ϫ 8 0 ϩ 012 Ϫ 5 0 4 ϩ 1Ϫ22 6 ϩ 1Ϫ22 106. 107. Chapter 1 Problem Recognition Exercises—Addition and Subtraction of Signed Numbers This set of exercises allows you to practice recognizing the difference between a negative sign and a subtraction sign in the context of a problem. 1. State the rule for adding two negative numbers. 21. Ϫ18 Ϫ 1Ϫ182 22. Ϫ3 Ϫ 1Ϫ32 2. State the rule for adding a negative number to 23. Ϫ3.5 Ϫ 4.2 24. Ϫ6.6 Ϫ 3.9 a positive number. 25. Ϫ90 ϩ 1Ϫ242 26. Ϫ35 ϩ 1Ϫ212 27. Ϫ14 ϩ 1Ϫ22 Ϫ 16 28. Ϫ25 ϩ 1Ϫ62 Ϫ 15 For Exercises 3–32, add or subtract as indicated. 3. 65 Ϫ 24 4. 42 Ϫ 29 29. Ϫ42 ϩ 12 ϩ 1Ϫ302 30. Ϫ46 ϩ 16 ϩ 1Ϫ402 5. 13 Ϫ 1Ϫ182 6. 22 Ϫ 1Ϫ242 31. Ϫ10 Ϫ 8 Ϫ 6 Ϫ 4 Ϫ 2 7. 4.8 Ϫ 6.1 8. 3.5 Ϫ 7.1 32. Ϫ100 Ϫ 90 Ϫ 80 Ϫ 70 Ϫ 60 9. 4 ϩ 1Ϫ202 10. 5 ϩ 1Ϫ122 For Exercises 33–34, evaluate the expression for x ϭ 3 1 5 3 1 11. Ϫ 12. Ϫ and y ϭ Ϫ5. 3 12 8 12 33. x Ϫ y 34. 0 x ϩ y 0 13. Ϫ32 Ϫ 4 14. Ϫ51 Ϫ 8 15. Ϫ6 ϩ 1Ϫ62 16. Ϫ25 ϩ 1Ϫ252 For Exercises 35–36, write an algebraic expression for each English phrase and then simplify the result. 35. The sum of Ϫ8 and 20. 17. Ϫ4 Ϫ aϪ b 18. Ϫ2 Ϫ aϪ b 5 2 6 5 36. The difference of Ϫ11 and Ϫ2. 19. Ϫ60 ϩ 55 20. Ϫ55 ϩ 23
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 89 BA CONFIRMING PAGES Section 1.5 Multiplication and Division of Real Numbers 89 Multiplication and Division of Real Numbers Section 1.5 1. Multiplication of Real Numbers Concepts Multiplication of real numbers can be interpreted as repeated addition. 1. Multiplication of Real Numbers 2. Exponential Expressions Example 1 Multiplying Real Numbers 3. Division of Real Numbers Multiply the real numbers by writing the expressions as repeated addition. 4. Applying the Order of Operations a. 3(4) b. 31Ϫ42 Solution: a. 3142 ϭ 4 ϩ 4 ϩ 4 ϭ 12 Add 3 groups of 4. b. 31Ϫ42 ϭ Ϫ4 ϩ 1Ϫ42 ϩ 1Ϫ42 ϭ Ϫ12 Add 3 groups of Ϫ4. The results from Example 1 suggest that the product of a positive number and a negative number is negative. Consider the following pattern of products. 4 ϫ 3 ϭ 12 4ϫ 2ϭ 8 The pattern decreases 4ϫ 1ϭ 4 by 4 with each row. 4ϫ 0ϭ 0 Thus, the product of a 4 ϫ Ϫ1 ϭ Ϫ4 positive number and a 4 ϫ Ϫ2 ϭ Ϫ8 negative number must be 4 ϫ Ϫ3 ϭ Ϫ12 negative for the pattern to continue. Now suppose we have a product of two negative numbers. To determine the sign, consider the following pattern of products. Ϫ4 ϫ 3 ϭ Ϫ12 Ϫ4 ϫ 2 ϭ Ϫ8 The pattern increases Ϫ4 ϫ 1 ϭ Ϫ4 by 4 with each row. Ϫ4 ϫ 0 ϭ 0 Ϫ4 ϫ Ϫ1 ϭ 4 Thus, the product of two Ϫ4 ϫ Ϫ2 ϭ 8 negative numbers must be positive for the Ϫ4 ϫ Ϫ3 ϭ 12 pattern to continue. We now summarize the rules for multiplying real numbers. Multiplication of Real Numbers 1. The product of two real numbers with the same sign is positive. 2. The product of two real numbers with different signs is negative. 3. The product of any real number and zero is zero.
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 90 BA CONFIRMING PAGES 90 Chapter 1 The Set of Real Numbers Example 2 Multiplying Real Numbers Multiply the real numbers. a. Ϫ81Ϫ42 b. Ϫ2.51Ϫ1.72 c. Ϫ71102 1Ϫ82 f. Ϫ aϪ b 1 2 7 d. e. 01Ϫ8.32 2 7 2 Solution: a. Ϫ81Ϫ42 ϭ 32 ⎫ Same signs. Product is positive. ⎬ b. Ϫ2.51Ϫ1.72 ϭ 4.25 ⎭ c. Ϫ71102 ϭ Ϫ70 ⎫ Different signs. Product is negative. ⎪ ⎬ 1Ϫ82 ϭ Ϫ4 1 d. ⎪ 2 ⎭ e. 01Ϫ8.32 ϭ0 The product of any real number and zero is zero. f. Ϫ aϪ b 2 7 7 2 14 ϭ Same signs. Product is positive. 14 ϭ1 Reduce to lowest terms. Skill Practice Multiply. 1. Ϫ9132 2. Ϫ61Ϫ62 3. 01Ϫ72 5. Ϫ a b 6. 1Ϫ1.221Ϫ4.82 4 3 4. 1.51Ϫ82 Ϫ 3 4 Observe the pattern for repeated multiplications. 1Ϫ121Ϫ12 1Ϫ121Ϫ121Ϫ12 1Ϫ121Ϫ121Ϫ121Ϫ12 1Ϫ121Ϫ121Ϫ121Ϫ121Ϫ12 ϭ1 ϭ 1121Ϫ12 ϭ 1121Ϫ121Ϫ12 ϭ 1121Ϫ121Ϫ121Ϫ12 ϭ Ϫ1 ϭ 1Ϫ121Ϫ12 ϭ 1Ϫ121Ϫ121Ϫ12 ϭ1 ϭ 1121Ϫ12 ϭ Ϫ1 The pattern demonstrated in these examples indicates that • The product of an even number of negative factors is positive. • The product of an odd number of negative factors is negative. 2. Exponential Expressions Recall that for any real number b and any positive integer, n: bn ϭ b ؒ b ؒ b ؒ b p ؒ b ⎧ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎩ n factors of b Skill Practice Answers 1. Ϫ27 2. 36 3. 0 Be particularly careful when evaluating exponential expressions involving neg- 4. Ϫ12 ative numbers. An exponential expression with a negative base is written with parentheses around the base, such as 1Ϫ22 4. 5. 1 6. 5.76
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 91 BA CONFIRMING PAGES Section 1.5 Multiplication and Division of Real Numbers 91 To evaluate 1Ϫ22 4, the base Ϫ2 is multiplied four times: 1Ϫ22 4 ϭ 1Ϫ221Ϫ221Ϫ221Ϫ22 ϭ 16 If parentheses are not used, the expression Ϫ24 has a different meaning: • The expression Ϫ24 has a base of 2 (not Ϫ2) and can be interpreted as Ϫ1 ؒ 24. Hence, Ϫ24 ϭ Ϫ1122122122122 ϭ Ϫ16 • The expression Ϫ24 can also be interpreted as the opposite of 24. Hence, Ϫ24 ϭ Ϫ12 ؒ 2 ؒ 2 ؒ 22 ϭ Ϫ16 Example 3 Evaluating Exponential Expressions Simplify. 1 3 a. 1Ϫ52 2 b. Ϫ52 c. aϪ b d. Ϫ0.43 2 Solution: a. 1Ϫ52 2 ϭ 1Ϫ521Ϫ52 ϭ 25 Multiply two factors of Ϫ5. b. Ϫ5 ϭ Ϫ1152152 ϭ Ϫ25 2 Multiply Ϫ1 by two factors of 5. 3 c. aϪ b ϭ aϪ b aϪ b aϪ b ϭ Ϫ 1 1 1 1 1 1 Multiply three factors of Ϫ . 2 2 2 2 8 2 d. Ϫ0.43 ϭ Ϫ110.4210.4210.42 ϭ Ϫ0.064 Multiply Ϫ1 by three factors of 0.4. Skill Practice Simplify. 7. Ϫ72 8. 1Ϫ72 2 9. 1Ϫ32 3 10. Ϫ33 3. Division of Real Numbers Two numbers are reciprocals if their product is 1. For example, Ϫ2 and Ϫ7 are reciprocals because Ϫ2 1Ϫ7 2 ϭ 1. Symbolically, if a is a nonzero real number, then 7 2 7 2 the reciprocal of a is 1 because a ؒ 1 ϭ 1. This definition also implies that a num- a a ber and its reciprocal have the same sign. The Reciprocal of a Real Number Let a be a nonzero real number. Then, the reciprocal of a is 1. a Recall that to subtract two real numbers, we add the opposite of the second number to the first number. In a similar way, division of real numbers is defined in terms of multiplication. To divide two real numbers, we multiply the first num- ber by the reciprocal of the second number. Division of Real Numbers Let a and b be real numbers such that b 0. Then, a Ϭ b ϭ a ؒ b. 1 Skill Practice Answers 7. Ϫ49 8. 49 9. Ϫ27 10. Ϫ27
• miL28711_ch01_049-120 9/20/06 11:37 AM Page 92 BA CONFIRMING PAGES 92 Chapter 1 The Set of Real Numbers Consider the quotient 10 Ϭ 5. The reciprocal of 5 is 1, so we have 5 multiply 1 10 Ϭ 5 ϭ 2 or equivalently, 10 ؒ ϭ2 5 reciprocal Because division of real numbers can be expressed in terms of multiplication, then the sign rules that apply to multiplication also apply to division. Division of Real Numbers 1. The quotient of two real numbers with the same sign is positive. 2. The quotient of two real numbers with different signs is negative. Example 4 Dividing Real Numbers Divide the real numbers. Ϫ48 Ϫ6.25 Ϫ9 a. 200 Ϭ 1Ϫ102 b. c. d. 16 Ϫ1.25 Ϫ5 2 3 9 e. 15 Ϭ Ϫ25 f. Ϫ Ϭ g. 5 14 7 Ϫ2 5 Solution: a. 200 Ϭ 1Ϫ102 ϭ Ϫ20 Different signs. Quotient is negative. Ϫ48 b. ϭ Ϫ3 Different signs. Quotient is negative. 16 Ϫ6.25 c. ϭ5 Same signs. Quotient is positive. Ϫ1.25 Ϫ9 9 TIP: If the numerator d. ϭ Same signs. Quotient is positive. Ϫ5 5 and denominator of a Because 5 does not divide into 9 evenly, the fraction are both negative, answer can be left as a fraction. then the quotient is Ϫ9 e. 15 Ϭ Ϫ25 Different signs. Quotient is negative. positive. Therefore, Ϫ5 can 9 be simplified to 5. 15 ϭ Ϫ25 3 ϭϪ 5 TIP: If the numerator and denominator of a fraction have opposite signs, then the quotient will be negative. Therefore, a fraction has the same value whether the negative sign is written in the numerator, in the denominator, or in front of the fraction. Ϫ3 3 3 ϭ ϭϪ 5 Ϫ5 5
• miL28711_ch01_049-120 11:16:2006 02:45 Page 93 BA CONFIRMING PAGES Section 1.5 Multiplication and Division of Real Numbers 93 3 9 f. Ϫ Ϭ Different signs. Quotient is negative. 14 7 3 7 ϭϪ ؒ Multiply by the reciprocal of 9 7 which is 7 . 9 14 9 21 ϭϪ Multiply fractions. 126 1 ϭϪ Reduce to lowest terms. 6 2 g. 5 This is equivalent to 2 Ϭ 1Ϫ2 2 . Ϫ2 5 5 5 aϪ b 2 5 ϭ Multiply by the reciprocal of Ϫ2, which is Ϫ5. 5 2 5 2 ϭ Ϫ1 Multiply fractions. Skill Practice Simplify. Ϫ20 18 Ϫ7 11. Ϫ14 Ϭ 7 12. 13. 14. Ϫ5 Ϫ3 Ϫ3 Ϫ4 Ϫ9 Ϫ1 Ϭa b 3 15. 16. 17. 18. 4.2 Ϭ Ϫ0.2 Ϫ8 4 16 1 Multiplication can be used to check any division problem. If a b ϭ c, then bc ϭ a (provided that b 0). For example, 1Ϫ421Ϫ22 ϭ 8 ✔ 8 ϭ Ϫ2 Check: Ϫ4 This relationship between multiplication and division can be used to investigate division problems involving the number zero. 1. The quotient of 0 and any nonzero number is 0. For example: 0 ϭ0 because 6 ؒ 0 ϭ 0 ✔ 6 2. The quotient of any nonzero number and 0 is undefined. For example, 6 ϭ? 0 Finding the quotient 6 is equivalent to asking, “What number times zero will equal 6?” That is, 1021?2 ϭ 6. No real number satisfies this condition. 0 Therefore, we say that division by zero is undefined. 3. The quotient of 0 and 0 cannot be determined. Evaluating an expression of the form 0 ϭ ? is equivalent to asking, “What number times zero will equal 0?” That is, 1021?2 ϭ 0. Any real number will satisfy this requirement; however, 0 expressions involving 0 are usually discussed in advanced mathematics courses. 0 Division Involving Zero Skill Practice Answers Let a represent a nonzero real number. Then, 11. Ϫ2 12. 4 13. Ϫ6 7 1 4 0 a 14. 15. 16. Ϫ 1. a ϭ 0 2. is undefined 3 2 3 0 17. –1 18. –21
• miL28711_ch01_049-120 9/20/06 11:38 AM Page 94 BA CONFIRMING PAGES 94 Chapter 1 The Set of Real Numbers 4. Applying the Order of Operations Example 5 Applying the Order of Operations 4 ϩ 130 Ϫ 5 Simplify the expressions. a. Ϫ36 Ϭ 1Ϫ272 Ϭ 1Ϫ92 b. Ϫ8 ϩ 8 Ϭ 1Ϫ22 Ϭ 1Ϫ62 24 Ϫ 23Ϫ3 ϩ 15 Ϫ 82 4 2 2 0Ϫ12 ϩ 3 0 c. d. Ϫ5 Ϫ 1 Solution: a. Ϫ36 Ϭ 1Ϫ272 Ϭ 1Ϫ92 ⎧ ⎪ ⎪ ⎨ ⎪ ⎪ ⎩ Ϫ36 ϭ Ϭ Ϫ9 Divide from left to right. Ϫ27 4 ϭ Ϭ Ϫ9 Reduce to lowest terms. 3 ϭ aϪ b 4 1 Multiply by the reciprocal of Ϫ9, which is Ϫ1. 9 3 9 4 ϭϪ The product of two numbers with opposite 27 signs is negative. b. Ϫ8 ϩ 8 Ϭ 1Ϫ22 Ϭ 1Ϫ62 ϭ Ϫ8 ϩ 1Ϫ42 Ϭ 1Ϫ62 Perform division before addition. 4 ϭ Ϫ8 ϩ The quotient of Ϫ4 and Ϫ6 is positive 4 6 or 2 . 3 6 8 2 ϭϪ ϩ Write Ϫ8 as a fraction. 1 3 24 2 ϭϪ ϩ Get a common denominator. 3 3 4 ϩ 130 Ϫ 5 22 ϭϪ Add. 3 4 ϩ 125 c. Simplify numerator and denominator separately. Ϫ5 Ϫ 1 ϭ Simplify within the radical and simplify the Ϫ6 denominator. 4ϩ5 ϭ Simplify the radical. Ϫ6 9 ϭ Ϫ6 3 3 ϭ or Ϫ Reduce to lowest terms. The quotient of two Ϫ2 2 numbers with opposite signs is negative.
• miL28711_ch01_049-120 9/20/06 11:38 AM Page 95 BA CONFIRMING PAGES Section 1.5 Multiplication and Division of Real Numbers 95 24 Ϫ 23Ϫ3 ϩ 15 Ϫ 82 4 2 2 0Ϫ12 ϩ 3 0 d. Simplify numerator and denominator separately. 24 Ϫ 23Ϫ3 ϩ 1Ϫ32 4 2 ϭ 2 0Ϫ9 0 Simplify within the inner parentheses and absolute value. 24 Ϫ 23 Ϫ64 2 ϭ Simplify within brackets, 3 4. Simplify the 2192 absolute value. 24 Ϫ 21362 ϭ Simplify exponents. 2192 24 Ϫ 72 ϭ Perform multiplication before subtraction. 18 Ϫ48 8 ϭ or Ϫ Reduce to lowest terms. 18 3 Ϫ4 Ϫ 112 Ϫ 8 Skill Practice Simplify. 19. Ϫ12 Ϭ 1Ϫ62 Ϭ 2 20. Ϫ32 Ϭ 4 ؒ 2 Ϫ 10 13 ϩ 152 Ϫ 1 Ϫ 2 ϩ 11 Ϫ6 Ϫ 1Ϫ42 21. 22. 12 ϩ 31Ϫ42 Example 6 Evaluating an Algebraic Expression Given y ϭ Ϫ6, evaluate the expressions. a. y2 b. Ϫy2 Solution: a. y2 ϭ1 22 When substituting a number for a variable, use parentheses. ϭ 1Ϫ62 2 Substitute y ϭ Ϫ6. ϭ 36 Square Ϫ6, that is, 1Ϫ621Ϫ62 ϭ 36. b. Ϫy2 ϭ Ϫ1 22 When substituting a number for a variable, use parentheses. ϭ Ϫ1Ϫ62 2 Substitute y ϭ Ϫ6. ϭ Ϫ1362 Square Ϫ6. ϭ Ϫ36 Multiply by Ϫ1. Skill Practice Given a ϭ –7, evaluate the expressions. 23a. a 2 b. Ϫa2 Skill Practice Answers 19. 1 20. Ϫ26 21. 3 22. Undefined 23a. 49 b. Ϫ49
• miL28711_ch01_049-120 9/20/06 11:38 AM Page 96 BA CONFIRMING PAGES 96 Chapter 1 The Set of Real Numbers Calculator Connections Be particularly careful when raising a negative number to an even power on a calculator. For example, the expressions 1Ϫ42 2 and Ϫ42 have different values. That is, 1Ϫ42 2 ϭ 16 and Ϫ42 ϭ Ϫ16. Verify these expressions on a calculator. Scientific Calculator To evaluate 1Ϫ42 2 Enter: ( 4 ϩրϪ ) x2 Result: 16 To evaluate Ϫ42 on a scientific calculator, it is important to square 4 first and then take its opposite. Enter: 4 x2 ϩրϪ Result: Ϫ16 Graphing Calculator The graphing calculator allows for several methods of denoting the multiplication of two real numbers. For example, consider the product of Ϫ8 and 4. Calculator Exercises Simplify the expression without the use of a calculator. Then use the calculator to verify your answer. Ϫ5.2 1. Ϫ6152 2. 3. 1Ϫ521Ϫ521Ϫ521Ϫ52 4. 1Ϫ52 4 2.6 5. Ϫ54 6. Ϫ2.42 7. 1Ϫ2.42 2 Ϫ8.4 8. 1Ϫ121Ϫ121Ϫ12 9. 10. 90 Ϭ 1Ϫ52122 Ϫ2.1 Section 1.5 Practice Exercises Boost your GRADE at • Practice Problems • e-Professors mathzone.com! • Self-Tests • Videos • NetTutor Study Skills Exercises 1. Look through the text, and write down the page number that contains: a. Avoiding Mistakes b. Tip box c. A key term (shown in bold) 2. Define the key term reciprocal of a real number.
• miL28711_ch01_049-120 9/20/06 11:38 AM Page 97 BA CONFIRMING PAGES Section 1.5 Multiplication and Division of Real Numbers 97 Review Exercises 6. 136 Ϫ 0 Ϫ6 0 7 0 7. 19 ϩ 0 Ϫ3 0 Յ 0 For Exercises 3–7, determine if the expression is true or false. 3. 6 ϩ 1Ϫ22 7 Ϫ5 ϩ 6 4. 0Ϫ6 0 ϩ 0 Ϫ14 0 Յ 0Ϫ3 0 ϩ 0Ϫ17 0 5. 16 Ϫ 0 Ϫ2 0 Յ 0Ϫ3 0 Ϫ 1Ϫ112 Concept 1: Multiplication of Real Numbers For each product in Exercises 8–11, write an equivalent addition problem. 8. 5(4) 9. 2(6) 10. 31Ϫ22 11. 51Ϫ62 For Exercises 12–19, multiply the real numbers. 12. 81Ϫ72 13. 1Ϫ32 ؒ 4 14. 1Ϫ62 ؒ 7 15. 91Ϫ52 16. 1Ϫ1121Ϫ132 17. 1Ϫ521Ϫ262 18. 1Ϫ3021Ϫ82 19. 1Ϫ1621Ϫ82 Concept 2: Exponential Expressions For Exercises 20–27, simplify the exponential expression. 20. 1Ϫ62 2 21. 1Ϫ102 2 22. Ϫ62 23. Ϫ102 2 3 5 3 24. aϪ b 25. aϪ b 26. 1Ϫ0.22 4 27. 1Ϫ0.12 4 3 2 Concept 3: Division of Real Numbers For Exercises 28–33, show how multiplication can be used to check the division problems. 14 Ϫ18 0 0 28. ϭ Ϫ7 29. ϭ3 30. ϭ0 31. ϭ0 Ϫ2 Ϫ6 Ϫ5 Ϫ4 6 Ϫ4 32. is undefined 33. is undefined 0 0 For Exercises 34–41, divide the real numbers. 54 Ϫ27 Ϫ100 Ϫ120 34. 35. 36. 37. Ϫ9 3 Ϫ10 Ϫ40 Ϫ14 Ϫ21 13 7 38. 39. 40. 41. Ϫ7 Ϫ3 Ϫ65 Ϫ77 Mixed Exercises For Exercises 42–117, multiply or divide as indicated. 42. 2 ؒ 3 43. 8 ؒ 6 44. 21Ϫ32 45. 81Ϫ62 46. 1Ϫ223 47. 1Ϫ826 48. 1Ϫ221Ϫ32 49. 1Ϫ821Ϫ62 50. 24 Ϭ 3 51. 52 Ϭ 2 52. 24 Ϭ 1Ϫ32 53. 52 Ϭ 1Ϫ22 54. 1Ϫ242 Ϭ 3 55. 1Ϫ522 Ϭ 2 56. 1Ϫ242 Ϭ 1Ϫ32 57. 1Ϫ522 Ϭ 1Ϫ22
• miL28711_ch01_049-120 9/20/06 11:38 AM Page 98 BA CONFIRMING PAGES 98 Chapter 1 The Set of Real Numbers 58. Ϫ6 ؒ 0 59. Ϫ8 ؒ 0 60. Ϫ18 Ϭ 0 61. Ϫ42 Ϭ 0 62. 0 aϪ b 63. 0 aϪ b 64. 0 Ϭ aϪ b 65. 0 Ϭ a b 2 1 1 4 5 8 10 9 Ϫ9 Ϫ15 Ϫ30 Ϫ250 66. 67. 68. 69. 6 10 Ϫ100 Ϫ1000 26 52 70. 71. 72. 1.721Ϫ4.62 73. 361.31Ϫ14.92 Ϫ13 Ϫ4 14.4 50.4 74. Ϫ0.021Ϫ4.62 75. Ϫ0.061Ϫ2.152 76. 77. Ϫ2.4 Ϫ6.3 Ϫ5.25 Ϫ8.5 78. 79. 80. 1Ϫ32 2 81. 1Ϫ72 2 Ϫ2.5 Ϫ27.2 4 3 1 3 82. Ϫ32 83. Ϫ72 84. aϪ b 85. aϪ b 3 5 86. 1Ϫ0.22 3 87. 1Ϫ0.12 6 88. Ϫ0.24 89. Ϫ0.14 90. 87 Ϭ 1Ϫ32 91. 96 Ϭ 1Ϫ62 92. Ϫ41Ϫ122 93. 1Ϫ521Ϫ112 94. 2.81Ϫ5.12 95. 17.2121Ϫ0.32 96. 1Ϫ6.82 Ϭ 1Ϫ0.022 97. 1Ϫ12.32 Ϭ 1Ϫ0.032 98. aϪ ba b 99. aϪ ba b 100. aϪ b Ϭ aϪ b 101. aϪ b Ϭ aϪ b 2 25 5 4 7 9 22 11 15 3 16 9 8 16 23 3 102. 1Ϫ221Ϫ521Ϫ32 103. 1Ϫ621Ϫ121Ϫ102 104. 1Ϫ821Ϫ421Ϫ121Ϫ32 105. 1Ϫ621Ϫ321Ϫ121Ϫ52 106. 100 Ϭ 1Ϫ102 Ϭ 1Ϫ52 107. 150 Ϭ 1Ϫ152 Ϭ 1Ϫ22 108. Ϫ12 Ϭ 1Ϫ62 Ϭ 1Ϫ22 109. Ϫ36 Ϭ 1Ϫ22 Ϭ 6 ؒ ؒ aϪ b 111. aϪ b ؒ aϪ b ؒ a1 b 112. a1 b Ϭ 3 Ϭ aϪ b 113. Ϫ Ϭ a3 b Ϭ 1Ϫ22 2 1 10 9 2 5 1 7 7 1 110. 5 3 11 8 3 12 3 9 8 4 114. 12 Ϭ 1Ϫ22142 115. 1Ϫ62 ؒ 7 Ϭ 1Ϫ22 116. aϪ b Ϭ 1Ϫ62 ؒ aϪ b 117. 10 ؒ Ϭ 12 1 1 25 5 8 3 6 Concept 4: Applying the Order of Operations For Exercises 118–131, perform the indicated operations. 118. 8 Ϫ 23 ؒ 5 ϩ 3 Ϫ 1Ϫ62 119. Ϫ14 Ϭ 1Ϫ72 Ϫ 8 ؒ 2 ϩ 33 120. Ϫ12 Ϫ 82 2 Ϭ 1Ϫ62 ؒ 2 61Ϫ42 Ϫ 215 Ϫ 82 31Ϫ42 Ϫ 519 Ϫ 112 121. Ϫ13 Ϫ 52 2 ؒ 6 Ϭ 1Ϫ42 122. 123. Ϫ6 Ϫ 3 Ϫ 5 Ϫ9 Ϫ 2 Ϫ 3 Ϫ4 ϩ 5 Ϫ3 ϩ 10 126. 0 Ϫ5 0 Ϫ 0 Ϫ7 0 1Ϫ22 ؒ 5 ϩ 10 124. 125. 21Ϫ42 ϩ 8
• miL28711_ch01_049-120 9/21/06 08:58 PM Page 99 BA CONFIRMING PAGES Section 1.5 Multiplication and Division of Real Numbers 99 127. 0Ϫ8 0 Ϫ 0Ϫ2 0 128. Ϫ 0Ϫ1 0 Ϫ 0 5 0 129. Ϫ 0Ϫ10 0 Ϫ 06 0 02 Ϫ 9 0 Ϫ 05 Ϫ 7 0 0 Ϫ2 ϩ 6 0 Ϫ 03 Ϫ 5 0 130. 131. 10 Ϫ 15 13 Ϫ 11 For Exercises 132–139, evaluate the expression for x ϭ Ϫ2, y ϭ Ϫ4, and z ϭ 6. 132. x2 Ϫ 2y 133. 3y2 Ϫ z 134. 412x Ϫ z2 3x ϩ 2y 2z Ϫ y 135. 613x ϩ y2 136. 137. y x x ϩ 2y xϪz 138. 139. x Ϫ 2y x2 Ϫ z2 141. Is the expression 10ր 15x2 equal to 10 10 140. Is the expression equal to 10 ր5x? Explain. ? Explain. 5x 5x For Exercises 142–149, translate the English phrase into an algebraic expression. Then evaluate the expression. 142. The product of Ϫ3.75 and 0.3 143. The product of Ϫ0.4 and Ϫ1.258 144. The quotient of 16 5 and 1Ϫ8 2 9 145. The quotient of 1Ϫ14 2 and 3 1 7 146. The number Ϫ0.4 plus the quantity 6 times Ϫ0.42 147. The number 0.5 plus the quantity Ϫ2 times 0.125 148. The number Ϫ1 minus the quantity 6 times Ϫ1 4 3 149. Negative five minus the quantity 1Ϫ5 2 times 6 3 8 150. For 3 weeks, Jim pays \$2 a week for lottery tickets. Jim has one winning ticket for \$3. Write an expression that describes his net gain or loss. How much money has Jim won or lost? 151. Stephanie pays \$2 a week for 6 weeks for lottery tickets. Stephanie has one winning ticket for \$5. Write an expression that describes her net gain or loss. How much money has Stephanie won or lost? 152. Evaluate the expressions in parts (a) and (b). a. Ϫ4 Ϫ 3 Ϫ 2 Ϫ 1 b. Ϫ41Ϫ321Ϫ221Ϫ12 c. Explain the difference between the operations in parts (a) and (b). 153. Evaluate the expressions in parts (a) and (b). a. Ϫ10 Ϫ 9 Ϫ 8 Ϫ 7 b. Ϫ101Ϫ921Ϫ821Ϫ72 c. Explain the difference between the operations in parts (a) and (b).