\[
\boxed{
{\frac {\rm d}{{\rm d}x}}y \left( x \right) ={\frac { \left( {x}^{3}+3\, \left( y \left( x \right)  \right) ^{2} \right) y \left( x \right) }{ \left( 6\, \left( y \left( x \right)  \right) ^{2}+x \right) x}}=0}
\]