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# TechMathII - 2.1 - Variables and Expressions

## by lmrhodes on Aug 28, 2010

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## TechMathII - 2.1 - Variables and ExpressionsPresentation Transcript

• Bell Ringer
• Solve the following for x = -2 and y = 4
• 2x – 8
• 3x + y
• -2x +4y – 8
• ½ y – 5x + 15
• 2x + 5y 2
• Please Excuse My Dear Aunt Sally! “Order of Operations”
• Parenthesis
• Exponents
• Multiplication
• Division
• Subtraction
• Examples
• Solve using the Order of Operations
• 1) 2 + 5 * 4
• 2) 3 * 2 - 8 2
• 3) 2 * 27 – 13 * 2
• 4) 4 * (8 – 2 * 3)
• 5) 18 (3 + 4)
• 3 + 8
• You try!
• Solve using the Order of Operations
• 1) 4 + 6 * 8
• 2) 40 / 5 * 2
• 3) 4 + 3 ( 15 – 2 3 )
• 4) 2(3 + 4)
• 7
• Examples
• Evaluate each expression for a = 2 and b = 3.
• 6) a + 2b
• 5
• 7) 5a + b
• 3
• 8) a + 3b 2
• 9) 7a – 4(b + 2)
• You try 2!
• Evaluate each expression for a = 3 and b = 5.
• 1) 3a – b 2
• 2) a – 9b 2a
• 3) 4a – 9b 2
• 4) 4 – 2a
• 3b
• Homework
• Order of Operations WS
• Bell Ringer
• Evaluate each expression for a = 5 and b = 8.
• 1) 2a – 3b 2
• 2) a – 4b 3a
• 3) 2a – 4b 2
• 4) 5 – 7a
• 4b
• Vocabulary
• Variable – a symbol (or a letter) that represents an unknown number
• Algebraic Expression – mathematical phrase that can include numbers, variables, and operation symbols
• Equation – mathematical sentence that uses an equal sign
• Constants – numbers
• Examples
• Write an algebraic expression for each phrase.
• 1) 6 more than k
• 2) y minus 5
• 3) the quotient of h and 20
• 4) the sum of 8 times 2 and t
• You try!
• Write an algebraic expression for each phrase.
• 1) 7 minus x
• 2) 12 more than y
• 3) the sum of x times 3 and r
• 4) the quotient of 9 and w
• Examples
• Define a variable and write an expression for each phrase.
• 5) 8 less than a number
• 6) a number divided by 8
• 7) 7 more than twice a number
• 8) 6 times the sum of w and 9
• You try 2!
• Define a variable and write an expression for each phrase.
• 1) A number plus negative nine
• 2) The product of 12 and a number
• 3) Eight more than three times a number
• 4) Three times the sum of two numbers
• Examples
• Define a variable and write an equation for each phrase.
• 9) The weight of a truck is two times the weight of a car.
• 10) The number of gallons of water used to water trees is 30 times the number of trees.
• 11) The number of pieces of pizza remaining from an 8-slice pizza after you have eaten some pieces.
• Homework