\[
\boxed{
x \left( y \left( x \right)  \right) ^{2} \left( {\frac {\rm d}{{\rm d}x}}y \left( x \right)  \right) ^{2}- \left(  \left( y \left( x \right)  \right) ^{3}+{x}^{3}-a \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) +{x}^{2}y \left( x \right) =0}
\]