Training Camp (cont 2)

When working with fractions, division by zero is undefined. In other words, the denominator of a fraction cannot equal zero. This also applies to rational expressions because they are a type of fraction.

In a fraction such as , you know the denominator is 3. This means you are not dividing by zero; therefore, there is no way for to be undefined.

What about a rational expression such as ? How do you know when it is undefined?

What you are really asking is this: "What values of x will make the denominator equal to zero?"

The values of x that make the denominator equal to zero are called non-permissible values.

To determine the non-permissible values set each factor in the denominator not equal (≠) to zero because these are the values of x that cannot be allowed.

Solve for x and you get 2.

Non-permissible values are also called restrictions because these values cannot be used otherwise will be undefined.

The non-permissible value stated as a restriction is x ≠ 2.