\[
\boxed{
{x}^{2} \left( {\frac {\rm d}{{\rm d}x}}y \left( x \right)  \right) ^{2}-2\,xy \left( x \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) + \left( y \left( x \right)  \right) ^{2} \left( -{x}^{2}+1 \right) -{x}^{4}=0}
\]