Question

How do you simplify `\frac { 1} { x + 3} - \frac { 9} { x ^ { 2} - 9} + \frac { 4} { x - 3}`?

Answer 1

I tried this:

Explanation:

We may remember that:
`x^2-9=(x+3)(x-3)`
and write:
`1/(x+3)-9/(x^2-9)+4/(x-3)=((x-3)-9+4(x+3))/(x^2-9)=(x-3-9+4x+12)/(x^2-9)=(5x)/(x^2-9)`