1. 4.4 Finding Slope and Rate of Change

2. How Would You Describe Slope?

3. Slope A ratio of the vertical change (rise) to the horizontal change (run) Rise/run Change in y/Change in x y2 – y1/x2 – x1

4. Examples: Find the Slope 1.(4, 3) (2, -1) 2.(-1, -1) (6, -2) 3.(8, 2) (3, 4) Can do these visually, see example 1 page 235, but do not rely on this as numbers start getting bigger!

5. Guided Practice 1-3 on Page 235

6. Horizontal and Vertical Lines (2, 1) (2, 9) (-7, 8) (-7, 10) (5, 4) (10, 4) (7, -2) (2, -2)

7. Guided Practice 4-6 page 236

8. What do the lines of these slopes look like? Positive Slope Negative Slope Zero Slope Undefined Slope

9. Rate of Change Compares a change in one quantity to a change in another quantity. Why is slope also a rate of change? Do guided practice #7

10. Extra Example (not in book- add to notes) The table shows the cost to paint a house for a given number of hours. Find the rate of change in cost with respect to time. Time (hours)468 Cost ($)90135180

11. Rates of Change and Line Graphs Break line graph into segments Find slope of each segment Use the slopes to describe the change

12. EXAMPLE 6 Use a graph to find and compare rates of change COMMUNITY THEATER A community theater performed a play each Saturday evening for 10 consecutive weeks. The graph shows the attendance for the performances in weeks 1, 4, 6, and 10. Describe the rates of change in attendance with respect to time.

13. Extra Example 7 The graph shows the number of computer games sold day 1, day 4, day 7 and day 9 of a sale. Describe the rates of change in sales with respect to time.

14. Interpreting a Graph Look over what is on each axis and what is being described. Decide what the different points on the graph are representing.

15. Example 7 and Guided Practice # 9

16. Find a Coordinate Given a Slope (0, y), (-2,1); m = -8 (-3, y + 1), (0, 4); m = 6

17. Review How do you find slope? What is rate of change and how do you find it? What are important things to look for when you’re interpreting a graph? How can you find a coordinate given a point and a slope?

18. Homework 1 – 6, 8 – 32 even, 33, 34, 36 – 40 Bonus Problems: 35, 41