This chapter discusses writing linear equations in slope-intercept form (y=mx+b) by either knowing the slope and y-intercept or by being given two points on the line. It provides examples of writing equations of lines from graphical representations or when given the slope and y-intercept numerically. Students are guided in writing linear equations from different scenarios like being given two points or the cost equation of a recording studio based on hours of studio time.

1. Chapter 5
Writing Linear Equations
A continuation of Chapter 4
Putting it all together
Focus is on the equation vs graphing
P. 283

2. • Section 5.1 Write a linear equation in the
Slope-Intercept Form
when: given the slope and Y-intercept
when: given the graph with the y-int.
Remember: Slope-Intercept Form is
y = mx + b, where m is the
slope and b is the y-intercept.

3. • Remember: Slope-Intercept Form is
y = mx + b, where m is the
slope and b is the y-intercept. (0,b)
• y = 3/4x – 5
slope is ¾ and the graph
crosses y at (0,-5)

4. EXAMPLE 1 Use slope and y-intercept to write an equation
Write an equation of the line with a slope of –2 and
a y-intercept of 5.
y = mx + b Write slope-intercept form.
y = –2x + 5 Substitute –2 for m and 5 for b.

5. GUIDED PRACTICE for Examples 1 and 2
Write an equation of the line with the given slope
and y-intercept.
1. Slope is 8; y-intercept is –7.
ANSWER y = 8x – 7

6. EXAMPLE 2 Standardized Test Practice
Which equation represents the line shown?
2
A y=– x+3 B y = – 5x + 3
5 2
2 2
C y=– x+1 D y = 3x + 5
5
The slope of the line is rise = –2 = – 2 .
run 5 5
The line crosses the y-axis at (0, 3). So, the
y-intercept is 3.
y = mx + b Write slope-intercept form.
y=– 2 x+3 Substitute – 2 for m and 3 for b.
5 5

7. EXAMPLE 3 Write an equation of a line given two points
Write an equation of the line shown.
Y = 4/3 x - 5

8. GUIDED PRACTICE for Examples 3 and 4
3. Write an equation of the line shown.
ANSWER y=– 1 x+1
2

9. • New Goal Today – given the y-int. and one
other point, how can you find the slope
and then write the equation? (without
graphing)

10. • Write the equation of a line that passes
through the points (4,5) (0,-2).
• Find the slope using the slope formula.
• Use the slope and Y-int to write the
equation.

11. • Write the equation of a line that passes
through the points (4, -2) (0,-2).
• Find the slope using the slope formula.
• Use the slope and Y-int to write the
equation.

12. • Write the equation of a line that passes
through the points (-6, -1) and (0,3).
• Find the slope using the slope formula.
• Use the slope and Y-int to write the
equation.

13. • A recording studio charges musicians an
initial fee of $50 to record an album. In
addition, studio time is $35 per hour.
• Write an equation that gives the total cost
of an album as a function of studio time (in
hours)
• Find the total cost of recording an album
that takes 10 hour of studio time.

14. • f(x) = 35x + 50 T = 35h + 50
• f(10) = 35(10) + 50
• f(10) = $400

15. • Assignment: P. 286 1-20, 24-29, 45-46