1. Constant of Proportionality

2. Direct Variation – constant ratio
A direct variation is represented by a ratio or equation : or
k ≠ 0
EX1)
Determine if the table represents a direct variation. If so, state the constant of proportionality
Step 1
Substitute values for variables x 1 2 3 4 y 6 9 12
Step 2
Simplify
This is a direct variation because the ratios are constant. The constant of proportionality is 3.
K = 3 3 3 3

3. EX2)
Identify the constant of proportionality in the equation y=15x where
y = cost of concert tickets and
x = number of concert tickets
y = 15 x
Explain the relationship.
Each concert ticket cost $15.
y = k x
k = constant of proportionality
15 = constant of proportionality
EX3)
Refer to the graph. Is there a direct variation? Explain
There is not a direct variation.
The line does not go through the origin.

4. notes

5. Constant of Proportionality
Date ____________
Constant of Proportionality

6. Direct Variation –
A direct variation is represented by a ratio or equation :
EX1)
Determine if the table represents a direct variation.
Step 1 x y
Step 2

7. EX2)
Identify the constant of proportionality.
Explain the relationship.
k =
y =
x =
y = 15 x
EX3)
Refer to the graph. Is there a direct variation? Explain