1. Direct Variation 3.6

2. Direct Variation  Direct Variation is when two variables can be expressed as y=kx where k is a constant and k is not 0.  k is called the constant of variation  Ex. y = 5x is direct variation while y = x + 5 is not

3. Example 1  Does the equation represent a direct variation?  2x – 3y = 0-x + y = 4

4. Example 2  Graph a direct variation equation  Y=2/3 xy = -3x

5. Write a direct variation Equation  Start with y = kx  Substitute a known x and y  Solve for k

6. Example 3  Write the equation for the direct variation represented in the graph.

7. Homework  p. 194-195: 3-9 all, 11-21 odd (graph paper and rulers needed), 23-25 all