Find the range of f(x)=ex−e−xex+e−xf(x) = \frac{e^x - e^{-x}}{e^x + e^{-x}}f(x)=ex+e−xex−e−x.
(−1,1)(-1, 1)(−1,1)
[0,1)[0, 1)[0,1)
R\mathbb{R}R
(−1,1](-1, 1](−1,1]