oh geez i hate i-ready's
Step-by-step explanation:
A linear function involves two variables which are in their first power form, such as x and y.
A nonlinear function may include two variables, one or more of which are of the 2nd or higher power.
y = x^2 - 2 is NOT a linear function, because of that power (2). Note how all the other choices show x to the 1st power.