\[
\boxed{
{\frac {\rm d}{{\rm d}x}}y \left( x \right) =1/2\,{\frac {-{x}^{2}+x+2+2\,{x}^{3}\sqrt {{x}^{2}-4\,x+4\,y \left( x \right) }}{1+x}}=0}
\]