Definition of a Function: For every “x” value there is only one “y” value

Given a Graph Given an Order Pair Domain and Range

Method

Use the Vertical Line Test

Draw light vertical lines through the graph. If a line passes through more than one point on the graph at the same time, then it is not a function.

Method

Use the definition of a function

Examine the domain (x-values) of the order pairs. If the same x-value appears with two different y-values, then it is not a function.

Method

Use the definition of a function

Examine the domain (x-values). If an x is pointing to two different y’s, then it is not a function.

This is not a function because the x-value (2), is paired to two different y-values (3 and -1)

Domain Range

– 5 3

2 0

1 – 4

– 7 – 2

This is not a function because the x value (1) is pointing to two different y’s (3 and – 2)

The Academic Support Center at Daytona State College (Math 13 pg 1 of 1)