1. Make sure you have the wksht completed from Friday!
Pre-Algebra
11-3
Using Slopes and Intercepts
Warm Up
Find the slope of the line that passes through each pair of points.
1. (3, 6) and (-1, 4)
2. (1, 2) and (6, 1)
3. (4, 6) and (2, -1)
4. (-3, 0) and (-1, 1) 1 2 - 1 5 7 2 1 2
Make sure you have the wksht completed from Friday!

2. use slopes and intercepts to graph linear equations

3. You can graph a linear equation easily by finding the x-intercept and the
y-intercept.
The x-intercept of a line is the value of x where the line crosses the x-axis (where y = 0).
The y-intercept of a line is the value of y where the line crosses the y-axis (where x = 0).

4. In an equation written in slope-intercept form, y = mx + b, m is the slope and b is the y-intercept.

5. For an equation such as y = x – 6, write it as
y = x + (–6) to read the y-intercept, –6.
Helpful Hint

6. Additional Example 2A: Using Slope-Intercept Form to Find Slopes and y-intercepts
Use the slope and y-intercept to graph.
y-int = slope = -3

7. Additional Example 2A: Using Slope-Intercept Form to Find Slopes and y-intercepts
Use the slope and y-intercept to graph.
y-int = 4 slope = ½

8. Additional Example 2A: Using Slope-Intercept Form to Find Slopes and y-intercepts
Find the slope and y-intercept and then graph.
A. y = 3 – 2x

9. Additional Example 2B: Using Slope-Intercept Form to Find Slopes and y-intercepts
B. y = 3x - 5

10. Additional Example 2C: Using Slope-Intercept Form to Find Slopes and y-intercepts
C. 3y = -4x + 9

11. Additional Example 2D: Using Slope-Intercept Form to Find Slopes and y-intercepts
C. 12x - 3y = -15

12. Additional Example 2E: Using Slope-Intercept Form to Find Slopes and y-intercepts
C. –y + 3x = 5

13. Additional Example 3: Entertainment Application
A video club charges $8 to join, and $1.25 for each DVD that is rented. The linear equation y = 1.25x + 8 represents the amount of money y spent after renting x DVDs. Graph the equation by first identifying the slope and y-intercept.

14. Additional Example 3 Continued
The slope of the line is 1.25, and the y-intercept is 8. The line crosses the y-axis at the point (0, 8) and moves up 1.25 units for every 1 unit it moves to the right.

15. Additional Example 4A: Writing Slope-Intercept Form
Write the equation of the line that passes through (3, –4) and (–1, 4) in slope-intercept form.

16. Additional Example 4B: Writing Slope-Intercept Form
Write the equation of the line that passes through (1, –4) and (–2, 2) in slope-intercept form.

17. Additional Example 5: Writing Slope-Intercept Form
Find the slope and y-intercept. Then write an equation in slope-intercept form. x y –2 5 –1 3 1 x y –3 –8 –1 –2 1 4 3 10

18. Additional Example 6: Writing Slope-Intercept Form
Find the slope and y-intercept. Then write an equation in slope-intercept form. x y 2 -2 4 -4