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