Sorry I'm crap at this..
1/x^2-1 - 2/x+1
I expanded x^2-1 then cross multiplied
which i got -2x+3 / (x+1)(x-1)
Would that be right? I'm not quite sure on this >< the negative signs screw me up alot.
I think it might be -2x-1 / (x+1)(x-1)
Please correct me :)
EDIT: can i cancel here? 4+k-1 / (k+3)(k-1)