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