What is a direct formula?

A direct formula is a formula that represents the proportionate change of two variables in the same direction such that when one variable increases/decreases the other variable also increases/decreases. The direct variation formula is a direct formula that maps two variables using a constant of variation.

The direct variation formula is written as y = kx; where, k is the constant of variation and y and x are the variables. The graph of the direct variation formula is a straight line in cases where the constant of variation is greater than zero. An example of a direct variation formula is the formula for the area of a circle.