1. 1)-1 – 4 2) 0 – (-2) 4 – ( -3) -1 – (-2) 3)3 – 4 4) 2 – (-2) 2 + 1 3 – 6

2. State Standard – 2.0 Students solve systems of linear equations. Objective – To be able to find the slopes of lines and classify parallel and perpendicular lines.

3. The Slope Of A Line The slope of the nonvertical line passing through the points (x 1,y 1 ) and (x 2,y 2 ) is: m = = y 2 – y 1 rise x 2 – x 1 run (x1,y1)(x1,y1) (x2,y2)(x2,y2) (y2 – y1)(y2 – y1) rise (x 2 – x 1 ) run

4. –5–4–3–2–112543 –5 –4 –3 –2 –1 1 2 5 4 3 Extra Example 3a Find the slope of the line passing through (-2,-4) and (3,-1). Solution: Let (x 1,y 1 ) = (-2,-4) and (x 2,y 2 ) = (3,-1). m = y 2 – y 1 x 2 – x 1 m = -1 – -4 3 – -2 m = -1 + 4 3 + 2 m = 3 5

5. rises (m>0) positive slope Classification Of Lines By Slope undefined slope (m is undefined) negative slope falls (m<0) zero slope (m=0)

6. Extra Example 3b Without graphing tell whether the line through the given points rises, falls, is horizontal, or is vertical. a. (-2,3), (1,5)b. (1, -2) and (3,-2) m = y 2 – y 1 x 2 – x 1 m = 5 – 3 1 – -2 m = 2 3 rises m = x 2 – x 1 m = -2 – -2 3 – 1 m = 0 2 horizontal y 2 – y 1

7. Slopes Of Parallel and Perpendicular Lines Lines are parallel only if they have the same slopes. m 1 = m 2 Lines are perpendicular only if their slopes are negative reciprocals of each other. m 1 = -1/m 2 or m 1 m 2 = -1

8. Due Tomorrow: Pg. 69 – 70 11 – 19, 51 – 57, 63, and 64