What Is a Dependent Variable?

In math, a dependent variable is one in an expression, equation or function that depends upon one or more other variables' values to determine its value. The dependent variable is usually isolated on one side of an equation. For example, "x" is the dependent variable in the equation x=y+1.

Independent and dependent variables are used both in mathematics equations and in the application of mathematics for scientific experimentation. In a scientific experiment, the independent variable is manipulated to demonstrate its impact on the dependent variable.

For instance, the amount of rainfall provided to two identical plants could be manipulated so that one plant received a rainfall value of one inch per week and the other plant received a rainfall value of two inches per week. Then, the plants could be measured for growth. The rainfall would be the independent variable while the growth would be the dependent variable.

Once the plant scientific experiment had been completed and replicated numerous time, predictions could be made about the impact of the independent rainfall variable on the dependent growth variable. This prediction would be expressed as a mathematical equation such as g=2r. In this expression, growth represented as "g", the dependent variable, occurs at twice the rate of the rainfall, represented as "r", provided, the independent variable.