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