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