Direct vs. indirect variation

A linear relationship between two variables,

written in the form

Y=KX or K= Huh?

What this means isthe Y’s will be the X’s times the same number

Direct variation

If Y divided by X always gives you the same

number then it is direct variation.

I remember this because direct and divide by start with “D”

Another short cut

Each X is multiplied by 3 to get the Y value

Example as table

X 1 2 3

Y 3 6 9

Example as graph

Y=3x

Y=1/2X

2y=X because divide both sides by 2 resulting Y=1/2X

Example as equation

1. Y=X+32. (0,0)(1,6)(2,12)

3.

You try which examples are direct variation

X 1 2 3

Y 4 5 6

Relationship between two variable

written Y= K/xHuh, again?

If Y equals a constant divided by a given X, then it is an inverse variation.

Inverse variation

If you multiple X and Y and they always equal

the same constant

then it is an inverse variation

Another short cut

Example as graph

x 6 2 12

y 6 18 3

Example as chart

This time you create a chart containing an

inverse variation.

You try

summary