\[ a x^3 \cos (x)+x y(x) y'(x)-y(x)^2=0 \] ✓ Mathematica : cpu = 0.220998 (sec), leaf count = 38
\[\left \{\left \{y(x)\to -x \sqrt {-2 a \sin (x)+c_1}\right \},\left \{y(x)\to x \sqrt {-2 a \sin (x)+c_1}\right \}\right \}\] ✓ Maple : cpu = 0.03 (sec), leaf count = 30
\[\left \{y \left (x \right ) = \sqrt {-2 a \sin \left (x \right )+c_{1}}\, x, y \left (x \right ) = -\sqrt {-2 a \sin \left (x \right )+c_{1}}\, x\right \}\]