\[ a x^3 \cos (x)+x y(x) y'(x)-y(x)^2=0 \] ✓ Mathematica : cpu = 0.0238753 (sec), leaf count = 38
\[\left \{\left \{y(x)\to -x \sqrt {c_1-2 a \sin (x)}\right \},\left \{y(x)\to x \sqrt {c_1-2 a \sin (x)}\right \}\right \}\]
✓ Maple : cpu = 0.03 (sec), leaf count = 30
\[ \left \{ y \left ( x \right ) =\sqrt {-2\,a\sin \left ( x \right ) +{\it \_C1}}x,y \left ( x \right ) =-\sqrt {-2\,a\sin \left ( x \right ) +{\it \_C1}}x \right \} \]