\[ \cos (y(x)) \left (\sin (y(x))-3 x^2 \cos (y(x))\right )+x y'(x)=0 \] ✓ Mathematica : cpu = 0.299695 (sec), leaf count = 21
\[\left \{\left \{y(x)\to \tan ^{-1}\left (\frac {2 x^3+c_1}{2 x}\right )\right \}\right \}\] ✓ Maple : cpu = 0.495 (sec), leaf count = 16
\[y \relax (x ) = \arctan \left (\frac {x^{3}+2 c_{1}}{x}\right )\]