\[ y'(x)=\frac {1}{3} x \left (3 x \sqrt {x^2+3 y(x)}-2\right ) \] ✓ Mathematica : cpu = 0.185588 (sec), leaf count = 31
DSolve[Derivative[1][y][x] == (x*(-2 + 3*x*Sqrt[x^2 + 3*y[x]]))/3,y[x],x]
\[\left \{\left \{y(x)\to \frac {1}{12} \left (x^6-6 c_1 x^3-4 x^2+9 c_1{}^2\right )\right \}\right \}\] ✓ Maple : cpu = 0.254 (sec), leaf count = 22
dsolve(diff(y(x),x) = 1/3*x*(-2+3*x*(x^2+3*y(x))^(1/2)),y(x))
\[c_{1}+\frac {x^{3}}{2}-\sqrt {x^{2}+3 y \left (x \right )} = 0\]