What is direct variation

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).

Direct variation means a mathematical relationship between two variables that can be expressed by an equation in which one variable is equal to a constant times the other.