# Defining and Comparing Functions

### Popular Tutorials in Defining and Comparing Functions

#### How Can You Tell if a Relation is Not a Function?

Every function is a relation, but not every relation is a function! Watch this video to learn how to tell which relations are functions and which are not.

#### How Do You Use the Vertical Line Test to Figure Out if a Graph is a Function?

Trying to figure out if an equation is a function? Graph it and perform the vertical line test. If it passes, then it's a function! Get some practice by watching this tutorial!

#### What's a Function?

You can't go through algebra without learning about functions. This tutorial shows you a great approach to thinking about functions! Learn the definition of a function and see the different ways functions can be represented. Take a look!

#### How Do You Find the Rate of Change Between Two Points in a Table?

The rate of change is a rate that describes how one quantity changes in relation to another quantity. This tutorial shows you how to use the information given in a table to find the rate of change between the values in the table. Take a look!

#### How Can You Tell if a Function is Linear or Nonlinear From a Table?

To see if a table of values represents a linear function, check to see if there's a constant rate of change. If there is, you're looking at a linear function! This tutorial shows you how to tell if a table of values represents a linear function.