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