1. 2.3: Direct Variation
Objective: Determine if a function is a direct variation function

2. Direct Variation k is the constant of variation
Ex1) Determine the direct variation equation of the given graph.
Characteristics of Direct Variation: 2

3. Using a Table
Does y vary directly with x in the following examples? (Check the ratio y/x)
Ex2)
Ex3) x y -1 3 2 -6 5 15 x y 7 14 9 18 -4 -8 3

4. Using Equations
Does y vary directly with x in the following equations? (Can the equation be written in the form y = kx ?) 4

5. Perimeter
Ex6) The perimeter of a square varies directly with the length of a side of the square.
a) Write a direct variation equation.
b) Find the constant of variation.
c) Find how long a side of the square must be for the perimeter to be 64 cm. 5

6. Using Proportions
Ex7) Suppose y varies directly with x, and y = 15 when
x = 27. Find y when x = 18. 6

7. Using Proportions Ex8) Suppose y varies directly with x.
If y = 4 when x = 3, then find y when x = 6
If y = 10 when x = -3, then find x when y = 2 7

8. Due WEDNESDAY!! Homework #12: Pg 71 #3-5
2.3: Direct Variation
Homework #12:
Pg 71 #3-5
Pg 74 # 1-19 odd, 23-27, 33, 34, 46
Due WEDNESDAY!!