\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) ={\frac {y \left ( x \right ) +\sqrt { \left ( y \left ( x \right ) \right ) ^{2}+{x}^{2}}{x}^{2}}{x}}=0} \]
Mathematica: cpu = 0.027003 (sec), leaf count = 20 \[ \left \{\left \{y(x)\to x \sinh \left (\frac {1}{2} \left (2 c_1+x^2\right )\right )\right \}\right \} \]
Maple: cpu = 0.920 (sec), leaf count = 30 \[ \left \{ \ln \left ( \sqrt { \left ( y \left ( x \right ) \right ) ^{2}+{ x}^{2}}+y \left ( x \right ) \right ) -{\frac {{x}^{2}}{2}}-\ln \left ( x \right ) -{\it \_C1}=0 \right \} \]