Se�t�te �adu pro $|x| \le 1$ (pou�ijte i Abelovu v�tu)
$$
\sum _{n=1}^{\infty }{\frac {{x}^{n}}{n\left (n+1\right )}}=-{
\frac {-x+\ln (1-x)x-\ln (1-x)}{x}} \quad .
$$
