1. 5.5: Direct Variation

2. A function in the form y = kx, where k ≠ 0, is a direct variation. The constant of variation k is the coefficient of x. The variables y & x are said to vary directly with each other. To determine if an equation is a direct variation, solve for y. Does it look like y = kx?

3. 5x + 2y = 0 3y + 4x = 8

4. To include point (4, -3) To include point (-3, -6)

5. You hear thunder 10 seconds after you see lightning which means you are 2 miles from the lightning. Given the relationship between when we hear thunder and where the lightning occurs varies directly, write an equation for the relationship between time and distance.

6. We can rewrite a direct variation y = kx as k = y/x Use the table to determine whether y varies directly with x. If it does write an equation. xyy/x -32.25 1-.75 4-3 6-4.5 xyy/x 2 41 63 94.5

7. The force you must apply to lift an object varies directly with the object’s weight. You would need to apply.625 lb. of force to a windlass to lift a 28 lb. weight. How much force would you need to lift 100 lbs?

8. p. 264 – 265 2-28 evens