DSolve[Derivative[1][y][x] == (3*x^3 + Sqrt[-9*x^4 + 4*y[x]^3] + x^2*Sqrt[-9*x^4 + 4*y[x]^3] + x^3*Sqrt[-9*x^4 + 4*y[x]^3])/y[x]^2,y[x],x]