1. Slope Special Section

2. SWBAT Understand the meaning of the word slope Find the slope using two points on a line Determine the difference between positive slope, negative slope, zero slope Show lines that have the same slope are parallel

3. Understanding Slope Slope is the ratio of the vertical change to the horziontal change In other words: Slope is the steepness of a line

4. Mathematical Facts about Slope Slope is denoted by the letter m The vertical change (change in y) is called the rise The horizontal change (change in x) is called the run

5. Mr. V, what are you talking about?

6. Find the Slope by Counting

7. Find the Slope by Graphing: Find the slope of a line that goes through points (- 3, 5) and (2,1) Plot the points

8. To solve by graphing: Start at the left dot and count down till you ’ re even with the right dot.

9. To solve by graphing: Now count over till you reach the right dot.

10. Now Solve We counted DOWN 4 spots, so we moved (– 4) units We counted RIGHT 5 spots, so we moved 5 units So our slope is: m = - 4/5 m = - 4/5

11. Using Math to Find Slope When given two points (x1, y1) and (x2, y2) you can find the slope of a line by using the following formula:

12. Slope Formula Continued

13. Example of a Negative Slope

14. GroupTry: Without graphing Find the Slope of a line through points (2,1) and (4,4) Remember: Hint: Identify (x1, y1) and (x2, y2)

15. Group Try: Find the Slope of a line through points (2,1) and (4,4)

16. Try on your own Find the slope through the points (7, -4) and (9, 4) Find the slope through the points (9, - 2) and (3, -5) Answer: m = 4 Answer: m = - ½

17. Slope and Steepness The greater the number, the steeper the slope (“faster” it moves up or down) The smaller the number, the more gentle the slope (“slower” it moves up or down) m = 4 >> m =1/4 >>

18. Classifying Slope Positive Slope – Slants up from left to right (“uphill”) Negative Slope – Slants down from left to right (“downhill”)

19. Classifying Slope Zero Slope – Line is horizontal (driving an a flat road) Undefined Slope – Line is vertical (straight up and down) – Can you drive a car up a wall? NO!

20. On Your Own: Label each slope as positive, negative, zero slope, or undefined

21. One More Quick Note Parallel lines have the same slope

22. In Your Group 1)What is the slope of the line represented by the table of values below? Answer: m = 10 xy 0- 20 1- 10 20 310

23. Which Graph has a Positive Slope? A B C D A!!

24. Which statement best describes the slope of the line graphed above? The slope is – 6 The slope is 2/3 The slope is 3/2 The slope is – 4 If you said: The slope is 2/3 You were WRONG! The slope is 3/2

25. Which line has the greatest slope? This Guy!!! 

26. Ticket to Leave Write the slope formula using m, x1, y1, x2, y2 Find the slope of the line that passes through the points (-2, 5) and (4, -5) Describe the difference between the graph of a line with a positive slope and a negative slope Describe the difference between the graph of a line with zero slope and undefined slope