# Excluded Value (Extraneous Solution)

How to find the excluded value (extraneous solution) of a rational expression: examples and their solutions.

## Example 1

The excluded value (extraneous solution) of a fraction

is the *x* value that makes the denominator 0.

To find the excluded value,

set '(denominator) = 0'.

3*x* - 2 = 0

Then *x* = 2/3.

This means *x* cannot be 2/3.

## Example 2

Before cancelling *x* + 4,

first find the excluded value.

Set '(denominator) = 0'.

(*x* + 4)(*x* - 6) = 0

Then *x* = -4, 6.

This means *x* cannot be -4 and 6.