\[
\boxed{
 \left( {\frac {\rm d}{{\rm d}x}}y \left( x \right)  \right) ^{2}+ \left( ay \left( x \right) +bx \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) +abxy \left( x \right) =0}
\]