DSolve[Derivative[1][y][x] == (x + (3*x^2)/2 - x*Cos[x] - 2*x^2*Cos[x] + (x^2*Cos[2*x])/2 + x^2*Sin[x] - 2*x*y[x] + 2*x*Cos[x]*y[x] + y[x]^2)/x,y[x],x]