Direct Variation

Direct Variation

Another way of describing a relationship between X and Y that is proportional

In direct variation, one variable will always be a constant multiple of the other.

Constant of Proportionality:

Situations that vary directly can always be represented with the equation

y = K x ( K is your CoP)

K = y/x

To find K you must divide Y by X

Open Ended

If x = 9 and y = 6 then.... k = ______________

What would your equation be? y= _______________

If x = 2 and y =15 then... k = ____________

What would your equation be? y= ____________

Now answer the following questions on your own.

Multiple Choice

If x = 10.5 and y = 21, what is the equation that represents the direct variation?

• y = -2x

• y = 2x

• y = .5x

• y = 1.5x

• y = 2/3x

Multiple Choice

If x= 20/3 and y = 10, what is the equation that represents the direct variation?

• y = -2x

• y = 2x

• y = .5x

• y = 1.5x

• y=2/3x