\[ \cos (y(x)) \left (\sin (y(x))-3 x^2 \cos (y(x))\right )+x y'(x)=0 \] ✓ Mathematica : cpu = 0.0888442 (sec), leaf count = 19
\[\left \{\left \{y(x)\to \tan ^{-1}\left (\frac {c_1}{2 x}+x^2\right )\right \}\right \}\]
✓ Maple : cpu = 0.425 (sec), leaf count = 16
\[ \left \{ y \left ( x \right ) =\arctan \left ( {\frac {{x}^{3}+2\,{\it \_C1}}{x}} \right ) \right \} \]