Question

Tell whether each equation represents a direct variation. if so, identify the constant of variation.

1. y=4x+9

2. 2y=-8x

3. x+y=0

Answer 1

1. Not a direct variation

2. Direct variation (constant= -4)

3. Direct variation (constant= -1)

Explanation:

A direct variation is a function of the type

y = k*x, where k can be any real number

First case

1. y=4x+9

The term 9 interferes with the expression (it creates an offset for the value)

2. 2y=-8x

It is a direct variation, y = -4x

3. x+y=0

It is a direct variation, y = -x