direct variation

Direct Proportion
Direct Variation
Directly Proportional

A relationship between two variables in which one is a constant multiple of the other. In particular, when one variable changes the other changes in proportion to the first.

If b is directly proportional to a, the equation is of the form b = ka (where k is a constant).

Equation: y = 4x

Variable y is directly proportional to x.

Doubling x causes y to double. Triplingx causes y to triple.

 x y 1 4 2 8 3 12