1. DIRECT VARIATION GOAL: WRITE AND GRAPH DIRECT VARIATION EQUATIONS Section 2-6:

2. Direct Variation Two variables x and y show direct variation, or vary directly, if y = kx where k is a nonzero constant called the constant of variation. The graph of y = kx is a line with slope k. The y- intercept is 0 (zero), so the graph of any direct variation equation passes through the origin.

3. Example 1: Graph y = 2x

4. Graph y = 2/3 x

5. Graph y = -4x

6. Example 2: A recipe for fruit punch uses 2 lemons to make 7 cups of punch. Write an equation relating the number of servings y to the number of lemons x. How many cups of punch can you make if you have 8 lemons?

7. Checkpoint: The variables x and y vary directly. Write an equation that relates x and y.  x= 3, y = -9 y = kx -9 = k*3 k =-3 y=-3x

8. Checkpoint: The variables x and y vary directly. Write an equation that relates x and y.  x = 10, y = 2 y = kx 2 = k*10 1/5 = k y = 1/5 x

9. P. 103-105 10-34 EVEN 50-66 EVEN HOMEWORK: