1. Warm Up Solve for y: 1) 2)

2. HW Check 4.7

3. CORE Time Complete the Puggly Wuggly Worksheet

4. Direct Variation A type of Linear Function

5. Direct Variation A function in the form y = kx, where k is the constant of variation. The variables y and x, “vary directly”! If the equation looks like y = kx, then it is DIRECT VARIATION!

6. Constant of Variation, k The constant of variation can be found by dividing y by x.

7. Is it DV? Is the equation Direct Variation? –Identify the constant k in each equation if it represents direct variation. 1. Y = 3x 2. Y = 4x + 1 3. Y = x 4. 2y = 8x 5. 5x + 2y = 0 6. 3x – y = 7

8. More facts about Direct Variation If the graph has the point (0,0), then it is DIRECT VARIATION!

9. Are these direct variation? a) b) c)

10. Writing a Direct Variation Equation Ex. 1: Write an equation of the direct variation that includes the point: (4, -3) Step1: Start with the direct variation equation Step 2: Substitute the x and y in the ordered pair for the x and y in the equation. Step 3: Solve for k. Step 4: Write the equation substituting k (in step 3) for k in the equation

11. You try! 2. Write a direct variation through the point (5, 2) 3. Write a direct variation through the point (-6, -6) 4. Write a direct variation through the point (-3, -12)

12. Direct Variation in a Table The value of k must be the same for all points!

13. Do the values vary directly?

14. Coming up… HW 4.8 tonight Quiz 4.2 Friday 11/15 Unit 4 Test – next Friday, 11/22