Find the range of f(x)=x2−4x2+1f(x) = \frac{x^2-4}{x^2+1}f(x)=x2+1x2−4.
[−4,1)[-4, 1)[−4,1)
(−1,1)(-1, 1)(−1,1)
[−4,1][-4, 1][−4,1]
[0,1)[0, 1)[0,1)