\[
\boxed{
 \left( 27\,{x}^{2}+4 \right) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) +27\,x{\frac {\rm d}{{\rm d}x}}y \left( x \right) -3\,y \left( x \right) =0}
\]