\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) =1/2\,x \left ( x+2\,\sqrt {{x}^{3}-6\,y \left ( x \right ) } \right ) =0} \]
Mathematica: cpu = 0.125016 (sec), leaf count = 33 \[ \left \{\left \{y(x)\to \frac {1}{24} \left (36 c_1 x^2-36 c_1^2-9 x^4+4 x^3\right )\right \}\right \} \]
Maple: cpu = 0.156 (sec), leaf count = 22 \[ \left \{ {\it \_C1}-{\frac {3\,{x}^{2}}{2}}-\sqrt {{x}^{3}-6\,y \left ( x \right ) }=0 \right \} \]