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

 

 

See also

Inverse variation, joint variation, gravity