How do I factorize this numerator? $$\lim_{x\to -3}   \frac 1{x+3} + \frac 4{x^2+2x-3}$$
I have the solution I just need to know how i turn that into:
$$\frac {(x-1)+4}{(x+3)(x-1)}$$
I know this might be really simple but I'm not sure how to factorise the numerator.
Thanks in advance!

You have
$$ x^2+2x-3 = (x-1)(x+3),$$
so
$$\frac{1}{x+3}+\frac{4}{x^2+2x-3}=\frac{1}{x+3}+\frac{4}{(x-1)(x+3)}=\frac{1(x-1) +4}{(x-1)(x+3)} $$
