\[ \left (y(x) f\left (x^2+y(x)^2\right )-x\right ) y'(x)+x f\left (x^2+y(x)^2\right )+y(x)=0 \] ✗ Mathematica : cpu = 299.998 (sec), leaf count = 0 , timed out
$Aborted
✓ Maple : cpu = 0.304 (sec), leaf count = 42
\[ \left \{ y \left ( x \right ) ={x \left ( \tan \left ( {\it RootOf} \left ( -2\,{\it \_Z}-\int ^{{\frac {{x}^{2} \left ( \left ( \tan \left ( {\it \_Z} \right ) \right ) ^{2}+1 \right ) }{ \left ( \tan \left ( {\it \_Z} \right ) \right ) ^{2}}}}\!{\frac {f \left ( {\it \_a} \right ) }{{\it \_a}}}{d{\it \_a}}+2\,{\it \_C1} \right ) \right ) \right ) ^{-1}} \right \} \]