# Math Help - Simplify Expression

1. ## Simplify Expression

Hi guys!
I need help with the simplification of:

(b^2 + 7b +12)/ (b^2 -9)

Any idea how to simplify further?

2. $\frac{b^2 + 7b +12}{ b^2 -9}=\frac{b^2+3b+4b+12}{(b+3)(b-3)}=\frac{b(b+3)+4(b+3)}{(b+3)(b-3)}=\frac{(b+3)(b+4)}{(b+3)(b-3)}=\frac{b+4}{b-3}$

3. Factorize both the numerator and denominator.

4. $x^2- 9$ as a fairly obvious factorization. You will be able to simplify (cancel) only if the numerator has a common factor with the denominator. And that will be true only if the same number makes both numerator and denominator 0. Clearly no positive number makes the numerator 0, so ...