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August 29, 2015
Posted by **K** on Tuesday, November 15, 2011 at 7:53pm.

- Math -
**MathMate**, Tuesday, November 15, 2011 at 8:15pmThis can be reduced to 12y=x³, or

y=x³/12

Direct variation have two properties:

1. it passes through the origin, i.e. if x=0, y=0.

This property is satisfied by the above equation.

2. x and y are both linear, i.e. if you multiply x by any finite number, y increases by the same ratio.

For example, for the above,

x=1, y=1/12

x=2, y=8/12 (y is increased 8 times instead of 2), so the equation is not a direct variation.

Example of a direct variation:

y=2x

x=1, y=2

x=2, y=4

x=7, y=14

So the ratios are always 2:

2/1 = 4/2 = 14/7 =2 (equals the coefficient of x).