\[
\boxed{
 \left\{ t{\frac {{\rm d}^{2}}{{\rm d}{t}^{2}}}x \left( t \right) +2\,{\frac {\rm d}{{\rm d}t}}x \left( t \right) +tx \left( t \right) =0,t{\frac {\rm d}{{\rm d}t}}x \left( t \right) -t{\frac {\rm d}{{\rm d}t}}y \left( t \right) -2\,y \left( t \right) =0 \right\} }
\]