Which function is represented by ∑n=0∞x2n+12n+1\sum_{n=0}^{\infty} \frac{x^{2n+1}}{2n+1}∑n=0∞2n+1x2n+1?
12ln(1+x1−x)\frac{1}{2} \ln(\frac{1+x}{1-x})21ln(1−x1+x)
ln(1+x)\ln(1+x)ln(1+x)
arctan(x)\arctan(x)arctan(x)
arctanh(x)\text{arctanh}(x)arctanh(x)