\[ y'(x)-\frac {y(x)-x f\left (a y(x)^2+x^2\right )}{a y(x) f\left (a y(x)^2+x^2\right )+x}=0 \] ✗ Mathematica : cpu = 299.998 (sec), leaf count = 0 , timed out
$Aborted
✓ Maple : cpu = 0.444 (sec), leaf count = 52
\[ \left \{ {1\arctan \left ( {x\sqrt {a}{\frac {1}{\sqrt {{a}^{2} \left ( y \left ( x \right ) \right ) ^{2}}}}} \right ) {\frac {1}{\sqrt {a}}}}-{\frac {1}{2}\int ^{ \left ( y \left ( x \right ) \right ) ^{2}+{\frac {{x}^{2}}{a}}}\!{\frac {f \left ( {\it \_a}\,a \right ) }{{\it \_a}}}{d{\it \_a}}}-{\it \_C1}=0 \right \} \]