Find the derivative of f(x)=ln(1+x1−x)f(x) = \ln(\sqrt{\frac{1+x}{1-x}})f(x)=ln(1−x1+x) for ∣x∣<1|x| < 1∣x∣<1.
11−x2\frac{1}{1-x^2}1−x21
11+x2\frac{1}{1+x^2}1+x21
21−x2\frac{2}{1-x^2}1−x22
11−x2\frac{1}{\sqrt{1-x^2}}1−x21