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