Answer:
2x
f(x) = -------------- or f(x) = 2x / (1-x^2)
1 - x^2
to eliminate any ambiguity. The graph of this function passes thru the origin (0,0) and has vertical asymptotes at x = -1 and x = + 1. The function is negative on (-1,0) and positive on (0,1).
Additionally, there are two horizontal asymptotes. As x grows large and negative, f(x) approaches zero from above. As x grows large and positive, f(x) approaches zero from below.
