# Introduction to nonlinear equations - Linear Equations

### Introduction to nonlinear equations

Non-linear equations, as it says in its name, are any functions that are not linear, for example, quadratic, circle and exponential functions. In this lesson, we will learn how to graph nonlinear equations, and then determine whether they are a function or not. The easiest way to verify if an equation is a function, no matter if it is linear or non-linear, is by using the vertical line test.