If the function ƒ : R – {1, –1} $ \to $ A defined by ƒ(x) = ${{{x^2}} \over {1 - {x^2}}}$ , is surjective, then A is equal to

Question

If the function ƒ : R – {1, –1} $ \to $ A defined by
ƒ(x) = ${{{x^2}} \over {1 - {x^2}}}$ , is surjective, then A is equal to

R – (–1, 0)