1. The Slope of a Line

2. Important things about slope… Slope is the change in y over change in x. Slope is represented by the letter m Vertical line has NO slope Horizontal line has a slope zero (0)

3. Formula for slope: = =

4. Find the slope of a line passing through points (1,1) and (3,-2)

5. A slope of - 3 / 2 means that or every time y goes down 3, x moves over 2 Graph and count to check. 1 2 3 4 -4 -3 -2 -4-3-2 123 4

6. Classify lines by their slope: 1. A line with a positive slope rises from left to right (m>0) x y

7. 2. A line with a negative slope falls down from left to right (m<0) x y

8. 3. A line with a zero slope is horizontal (m=0) Equation y = 3 x y

9. 4. A line with an undefined slope is vertical (m is undefined) YOU CANT DIVIDE BY 0! x y

10. RATE OF CHANGE: At 3:00 p.m. a car leaves the city. By 5:00 it has traveled 90 miles. Find its average speed. Change in miles Change in time(hours) Notice you have two pairs: (3,0) and (5,90) Where x is time and y is miles.

11. The temp. is 63 F at 7a.m. By 10a.m., its 45 F. Find the average rate of change in temp. Change in temp Change in time = -6 degrees per hour Two pairs: (7,63) and (10,45)

12. Find the value of y for the line going through points (-3, -2), (1, y) when the slope of the line is 2 2 = -2 – y -3 - 1 2 = -2 – y -4 -8 = -2 - y 6 = y