\[
\boxed{
x \left( {x}^{2}-1 \right) {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) +{\frac {\rm d}{{\rm d}x}}y \left( x \right) +y \left( x \right) a{x}^{3}=0}
\]