Could you explain where you are running into problems and maybe I can help you get past them. I don't think you learn much if I just do the problem for you.
How can i simplify the denominator ?
Hint: recall the difference of 2 squares.
Think of the denominator as (a-b)
Think you can take it from here? Think about it for a minute or two and if you still can't get it, let me know.
Why have you got brackets in the denoninator?