Our restriction is that the denominator of a fraction can never be
equal to 0.

So to find what values we need to exclude, think of what value(s) of *x*,
if any, would cause the denominator to be 0.

This give us a better look at it.

Since 0 would make the first factor in the denominator 0, then **0
would have to be excluded.**

Since 4 would make the second factor in the denominator 0, then **4
would also have to be excluded.**

**AND**

***Factor
the GCF in the num. and **

***Factor
the diff. of squares in the den. **

***Divide out the common factor of ( a + 4)**

***Rational expression simplified**

To find the value(s) needed to be excluded from the domain, we need
to ask ourselves, what value(s) of *a* would
cause our denominator to be 0?

Looking at the denominator *a* - 4, I would
say it would have to be *a* = 4. Don't
you agree?

**4 would be our excluded value.**

**AND**

***Factor
the trinomial in the den.**

***Factor out a -1 from (8 - x)**

***Divide out the common factor of ( x - 8)**

***Rational expression simplified**

To find the value(s) needed to be excluded from the domain, we need
to ask ourselves, what value(s) of *x* would
cause our denominator to be 0?

Looking at the denominator *x* + 1, I would
say it would have to be *x* = -1. Don't
you agree?

**-1 would be our excluded value.**

Last revised on Dec. 14, 2009 by Kim Seward.

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