f(x,y)=(x)/ (1-y2), y does not equal 1 or -1

Is it possible to define a new function g(x,y) that is defined and continuous for all (x,y) in R2, and such that g(x,y)=f(x,y) for all (x,y) in the domain of f? If so, find such a function. If not, explain why.

I really don't know where to begin...