\[ \cos (y(x)) \left (\sin (y(x))-3 x^2 \cos (y(x))\right )+x y'(x)=0 \] ✓ Mathematica : cpu = 0.0850783 (sec), leaf count = 21
\[\left \{\left \{y(x)\to \tan ^{-1}\left (\frac {c_1+2 x^3}{2 x}\right )\right \}\right \}\] ✓ Maple : cpu = 0.42 (sec), leaf count = 16
\[ \left \{ y \left ( x \right ) =\arctan \left ( {\frac {{x}^{3}+2\,{\it \_C1}}{x}} \right ) \right \} \]