\[ y'(x)=\frac {\csc \left (\frac {y(x)}{2 x}\right ) \sec \left (\frac {y(x)}{2 x}\right ) \sec \left (\frac {y(x)}{x}\right ) \left (x^3 \sin \left (\frac {y(x)}{2 x}\right ) \sin \left (\frac {y(x)}{x}\right ) \cos \left (\frac {y(x)}{2 x}\right )-\frac {1}{2} y(x) \sin \left (\frac {y(x)}{x}\right )+\frac {1}{2} y(x) \sin \left (\frac {y(x)}{2 x}\right ) \cos \left (\frac {y(x)}{2 x}\right )+\frac {1}{2} y(x) \sin \left (\frac {3 y(x)}{2 x}\right ) \cos \left (\frac {y(x)}{2 x}\right )\right )}{x} \] ✓ Mathematica : cpu = 0.0479333 (sec), leaf count = 20
\[\left \{\left \{y(x)\to x \sin ^{-1}\left (e^{c_1+\frac {x^2}{2}}\right )\right \}\right \}\]
✓ Maple : cpu = 0.085 (sec), leaf count = 15
\[ \left \{ y \left ( x \right ) =\arcsin \left ( {{\rm e}^{{\frac {{x}^{2}}{2}}}}{\it \_C1} \right ) x \right \} \]