Pomoc� rozvoje 
$$
(1+x)^\alpha = \sum _{n=1}^{\infty }
{\alpha \choose n} {x}^{n}
$$
platn�ho pro $\vert x \vert < 1$ spo�teme
$$
\left (1+x\right )^{-2}=(1-2\,
x+3\,{x}^{2}-4\,{x}^{3}+5\,{x}
^{4}+O\left ({x}^{5}\right ))
$$
a podobn� 
$$
\left (1-x\right )^{-1}=(1-2\,
x+3\,{x}^{2}-4\,{x}^{3}+5\,{x}
^{4}+O\left ({x}^{5}\right )) \quad .
$$
Vyn�soben�m t�chto �ad z�sk�me v�sledek.
