1. Copyright © 2006 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Slope Rate and Slope Horizontal and Vertical Lines Applications 3.5

2. Slide 3- 2 Copyright © 2006 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Slope The slope of the line containing points (x 1, y 1 ) and (x 2, y 2 ) is given by Change in y Change in x

3. Slide 3- 3 Copyright © 2006 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Example Graph the line containing the points (  4, 5) and (4,  1) and find the slope. Solution Change in y =  6 Change in x = 8

4. Slide 3- 4 Copyright © 2006 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Example Find the slope of the line y = 3 Solution Consider the points (  3, 3) and (2, 3), which are on the line. A horizontal line has slope 0. (  3, 3) (2, 3)

5. Slide 3- 5 Copyright © 2006 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Example Find the slope of the line x = 2 Solution Consider the points (2, 4) and (2,  2), which are on the line. The slope of a vertical line is undefined. (2, 4) (2,  2)

6. Slide 3- 6 Copyright © 2006 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Applications of Slope Some applications use slope to measure the steepness. For examples, numbers like 2%, 3%, and 6% are often used to represent the grade of a road, a measure of a road’s steepness. That is, a 3% grade means that for every horizontal distance of 100 ft, the road rises or drops 3 ft.

7. Slide 3- 7 Copyright © 2006 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Example Find the slope (or grade) of the treadmill. 0.42 ft 5.5 ft Solution The grade of the treadmill is 7.6%. ** Reminder: Grade is slope expressed as a percent.