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