\[
\boxed{
{\it d4y} \left( x \right) +10\,f{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) +10\,{\it df}\,{\frac {\rm d}{{\rm d}x}}y \left( x \right) + \left( 3\,{f}^{2}+3\,{\it ddf} \right) y \left( x \right) =0}
\]