Sorry I'm crap at this..

simplify

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 :)

Thanks

EDIT: can i cancel here? 4+k-1 / (k+3)(k-1)