\item{i} Pro {$ x=0  $} by muselo platit {$ 1+x^{2}=0, $} body {$ (0,y),
\,y\in \er_{2} $} neproch�z� ��dn� �e�en�.
\item{ii} Pro {$ x\neq 0 $} u�ijeme separaci prom�nn�ch:
$$
  \align
  \frac{y'}{1+y^{2}}&=\frac{1}{x}\cr
  \operatorname{arctg} y &= \ln cx \quad (cx>0)\cr
  y&=\operatorname{tg} (\ln cx),\quad c\neq 0, cx>0, |x|\in \left(
  \frac{e^{-\pi /2}}{|c|},\frac{e^{\pi /2}}{|c|}\right)\cr
   \endalign
$$