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