\[ y'(x)=\frac {x^4 \left (-\sqrt {x^2+y(x)^2}\right )+x^3 y(x) \sqrt {x^2+y(x)^2}+y(x)}{x} \] ✓ Mathematica : cpu = 0.305299 (sec), leaf count = 221
\[\left \{\left \{y(x)\to \frac {x-2 \sqrt {x^2 \tanh ^2\left (\frac {1}{4} \left (-\sqrt {2} x^4-4 \sqrt {2} c_1\right )\right )-x^2 \tanh ^4\left (\frac {1}{4} \left (-\sqrt {2} x^4-4 \sqrt {2} c_1\right )\right )}}{-1+2 \tanh ^2\left (\frac {1}{4} \left (-\sqrt {2} x^4-4 \sqrt {2} c_1\right )\right )}\right \},\left \{y(x)\to \frac {x+2 \sqrt {x^2 \tanh ^2\left (\frac {1}{4} \left (-\sqrt {2} x^4-4 \sqrt {2} c_1\right )\right )-x^2 \tanh ^4\left (\frac {1}{4} \left (-\sqrt {2} x^4-4 \sqrt {2} c_1\right )\right )}}{-1+2 \tanh ^2\left (\frac {1}{4} \left (-\sqrt {2} x^4-4 \sqrt {2} c_1\right )\right )}\right \}\right \}\] ✓ Maple : cpu = 0.301 (sec), leaf count = 49
\[\left \{\frac {\sqrt {2}\, x^{4}}{4}-c_{1}-\ln \left (x \right )+\ln \left (\frac {2 \left (x +y \left (x \right )+\sqrt {2 x^{2}+2 y \left (x \right )^{2}}\right ) x}{-x +y \left (x \right )}\right ) = 0\right \}\]