\[ y'(x)=\frac {\csc \left (\frac {y(x)}{2 x}\right ) \sec \left (\frac {y(x)}{2 x}\right ) \sec \left (\frac {y(x)}{x}\right ) \left (-\frac {1}{2} x y(x) \sin \left (\frac {y(x)}{x}\right )-\frac {1}{2} y(x) \sin \left (\frac {y(x)}{x}\right )+x \sin \left (\frac {y(x)}{2 x}\right ) \sin \left (\frac {y(x)}{x}\right ) \cos \left (\frac {y(x)}{2 x}\right )+\frac {1}{2} x y(x) \sin \left (\frac {y(x)}{2 x}\right ) \cos \left (\frac {y(x)}{2 x}\right )+\frac {1}{2} y(x) \sin \left (\frac {y(x)}{2 x}\right ) \cos \left (\frac {y(x)}{2 x}\right )+\frac {1}{2} x y(x) \sin \left (\frac {3 y(x)}{2 x}\right ) \cos \left (\frac {y(x)}{2 x}\right )+\frac {1}{2} y(x) \sin \left (\frac {3 y(x)}{2 x}\right ) \cos \left (\frac {y(x)}{2 x}\right )\right )}{x (x+1)} \] ✓ Mathematica : cpu = 0.240143 (sec), leaf count = 19
DSolve[Derivative[1][y][x] == (Csc[y[x]/(2*x)]*Sec[y[x]/(2*x)]*Sec[y[x]/x]*(x*Cos[y[x]/(2*x)]*Sin[y[x]/(2*x)]*Sin[y[x]/x] + (Cos[y[x]/(2*x)]*Sin[y[x]/(2*x)]*y[x])/2 + (x*Cos[y[x]/(2*x)]*Sin[y[x]/(2*x)]*y[x])/2 - (Sin[y[x]/x]*y[x])/2 - (x*Sin[y[x]/x]*y[x])/2 + (Cos[y[x]/(2*x)]*Sin[(3*y[x])/(2*x)]*y[x])/2 + (x*Cos[y[x]/(2*x)]*Sin[(3*y[x])/(2*x)]*y[x])/2))/(x*(1 + x)),y[x],x]
\[\left \{\left \{y(x)\to x \sin ^{-1}\left (\frac {e^{c_1} x}{x+1}\right )\right \}\right \}\] ✓ Maple : cpu = 0.09 (sec), leaf count = 15
dsolve(diff(y(x),x) = 1/2*(y(x)*sin(3/2*y(x)/x)*cos(1/2*y(x)/x)*x+y(x)*sin(3/2*y(x)/x)*cos(1/2*y(x)/x)+y(x)*cos(1/2*y(x)/x)*sin(1/2*y(x)/x)*x+y(x)*cos(1/2*y(x)/x)*sin(1/2*y(x)/x)-sin(y(x)/x)*y(x)*x-y(x)*sin(y(x)/x)+2*sin(y(x)/x)*cos(1/2*y(x)/x)*sin(1/2*y(x)/x)*x)/cos(y(x)/x)/sin(1/2*y(x)/x)/x/cos(1/2*y(x)/x)/(1+x),y(x))
\[y \left (x \right ) = \arcsin \left (\frac {x c_{1}}{1+x}\right ) x\]