Show that the function f(x)=x/(x^2-1) is a bijection between (-1,1) and the real numbers.

I was able to show that the function is one-to-one and y=x, but I can't figure out how to show that it is onto.

How can I also show that given any a and b, which are elements of the real numbers with a<b, there is a bijection between (a,b) and (-1,1).