\[
\boxed{
{\frac {\rm d}{{\rm d}x}}y \left( x \right) =-1/4\,{\frac { \left( y \left( x \right)  \right) ^{2}}{x} \left( 2\,x-F \left( -1/2\,{\frac {xy \left( x \right) -2}{y \left( x \right) }} \right)  \right) }=0}
\]