\[ \boxed { \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}-2\,{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) - \left ( y \left ( x \right ) \right ) ^{2}=0} \]
Mathematica: cpu = 0.061508 (sec), leaf count = 73 \[ \left \{\left \{y(x)\to \text {InverseFunction}\left [-\frac {\sqrt {\text {$\#$1}^2+1}}{\text {$\#$1}}-\frac {1}{\text {$\#$1}}+\sinh ^{-1}(\text {$\#$1})\& \right ]\left [c_1-x\right ]\right \},\left \{y(x)\to \text {InverseFunction}\left [-\frac {\sqrt {\text {$\#$1}^2+1}}{\text {$\#$1}}+\frac {1}{\text {$\#$1}}+\sinh ^{-1}(\text {$\#$1})\& \right ]\left [c_1+x\right ]\right \}\right \} \]
Maple: cpu = 0.406 (sec), leaf count = 85 \[ \left \{ x- \left ( y \left ( x \right ) \right ) ^{-1}-{\frac {1}{y \left ( x \right ) } \left ( \left ( y \left ( x \right ) \right ) ^{2}+1 \right ) ^{{\frac {3}{2}}}}+y \left ( x \right ) \sqrt { \left ( y \left ( x \right ) \right ) ^{2}+1}+{\it Arcsinh} \left ( y \left ( x \right ) \right ) -{\it \_C1}=0,x- \left ( y \left ( x \right ) \right ) ^{-1}+{\frac {1}{y \left ( x \right ) } \left ( \left ( y \left ( x \right ) \right ) ^{2}+1 \right ) ^{{\frac {3}{2}}}}-y \left ( x \right ) \sqrt { \left ( y \left ( x \right ) \right ) ^{2}+1}-{\it Arcsinh} \left ( y \left ( x \right ) \right ) -{\it \_C1}=0 \right \} \]