1. Warm Up Add or subtract. 1. 4 + (–6)2. –3 + 5 3. –7 – 74. 2 – (–1) –2 –14 2 3 5. Find the x- and y-intercepts of 2x – 5y = 20. x-int.: 10; y-int.: –4

2. Warm Up –part 2 Describe the correlation shown by the scatter plot. 6. negativepositivenegative positive

3. Slope Lesson 5.3

4. Preparation for 8.0 Students understand the concepts of parallel lines and perpendicular lines and how their slopes are related. Students are able to find the equation of a line perpendicular to a given line that passes through a given point. Also covered: 6.0 California Standards

5. Objectives Graph linear functions, noting that the vertical change per unit of horizontal change is always the same and is called the slope of a line (AF 3.3) Fit a line to a plot and understand that the slope of the line equals the ratio of the quantities (AF 3.4)

6. a nonvertical line is the ratio of the rise to the run between any two points on the line. Slope = “steepness” of a line. Slope Slope –

7. Slope Run = 4 Rise =–2 Run = –4 Rise = 2

8. Find the slope of the line. Begin at one point and count vertically to find the rise. Then count horizontally to the second point to find the run. Run = 4 Rise =–2 Run = –4 Rise = 2 Rise run

9. Finding Slopes of Horizontal and Vertical Lines A. B. The slope is undefined.The slope is 0.

10. Real World Slope

12. Find the slope of the line

14. How do you find the slope on the graph?

15. Kinds of Slopes (It helps to remember how you would walk on these lines.) Positive slope – walking up hill. Negative slope – walking down a hill. No slope – walking on level ground

16. Comparing Slopes Can you identify what is happening to the slopes?

17. Let’s practice- find the slope of the line.

18. Try again (we’re not convinced yet)

19. Find a slope of two points (2, 5) and (8, 1). (x 1, y 1 ) (x 2, y 2 ). Use the slope formula. Substitute (2, 5) for (x 1, y 1 ) and (8, 1) for (x 2, y 2 ).

20. Find a slope of two points (5, –7) and (6, –4) (x 1, y 1 ) (x 2, y 2 ). Rise Run yxyx 5 6 -7 -4 +3 x y +1 3131

21. Find a slope of two points (5, 3) and (–1, 4) (x 1, y 1 ) (x 2, y 2 ). Rise Run yxyx 5 -1 3 4 +1 x y -6 1 -6

22. Find a slope of two points (1, 3) and (–2, 1) (x 1, y 1 ) (x 2, y 2 ). Rise Run yxyx 1 -2 3 1 -2 x y -3 -2 -3 2323

23. And one last laugh…

24. Summary The constant rate of change of a nonvertical line is called the slope. If you know 2 different points on a line, you can use the slope formula to find the slope of the line If you know the equation of a line, you can also find the slope by using any two ordered-pair solutions Slope can be positive, negative, zero, and undefined

25. Lesson Quiz Find the slope of each line. undefined 1.2.

26. Lesson Quiz –part 2 3. Find the slope of the line that contains (5, 3) and (–1, 4). 4. Find the slope. Then tell what the slope represents. A slope of 50 means that the speed of the bus is 50 mi/h. 50 5. Find the slope of the line given by x – 2y = 8.