The equation of a linear function<span> has no exponents higher than 1, and the graph of a </span>linear function<span> is a straight line. The equation of a </span>nonlinear function<span> has at least one exponent higher than 1, and the graph of a </span>nonlinear function<span> is a curved line.</span>
A linear function has a constant additive rate of change, while a nonlinear function does not. For a table of values to be linear, the dependent variable must have a constant rate of change as the independent variable increases by 1. On a graph, the function must be a straight line to be linear.