\[
\boxed{
xy \left( x \right)  \left( {\frac {\rm d}{{\rm d}x}}y \left( x \right)  \right) ^{2}+ \left( {x}^{22}- \left( y \left( x \right)  \right) ^{2}+a \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) -xy \left( x \right) =0}
\]