\[
\boxed{
{\frac {\rm d}{{\rm d}x}}y \left( x \right) =1/2\,{\frac {-\sin \left( 2\,y \left( x \right)  \right) x-\sin \left( 2\,y \left( x \right)  \right) +x\cos \left( 2\,y \left( x \right)  \right) +x}{x \left( 1+x \right) }}=0}
\]