\[ y'(x)=\frac {\sqrt {4 y(x)^3-9 x^4}+3 x^3+x^3 \sqrt {4 y(x)^3-9 x^4}+x^2 \sqrt {4 y(x)^3-9 x^4}}{y(x)^2} \] ✓ Mathematica : cpu = 6.19974 (sec), leaf count = 227
\[\left \{\left \{y(x)\to -\frac {1}{2} \sqrt [3]{-\frac {1}{2}} \sqrt [3]{72 c_1 x^4+96 c_1 x^3+288 c_1 x+144 c_1^2+9 x^8+24 x^7+16 x^6+72 x^5+132 x^4+144 x^2}\right \},\left \{y(x)\to \frac {\sqrt [3]{72 c_1 x^4+96 c_1 x^3+288 c_1 x+144 c_1^2+9 x^8+24 x^7+16 x^6+72 x^5+132 x^4+144 x^2}}{2 \sqrt [3]{2}}\right \},\left \{y(x)\to \frac {(-1)^{2/3} \sqrt [3]{72 c_1 x^4+96 c_1 x^3+288 c_1 x+144 c_1^2+9 x^8+24 x^7+16 x^6+72 x^5+132 x^4+144 x^2}}{2 \sqrt [3]{2}}\right \}\right \}\] ✓ Maple : cpu = 0.248 (sec), leaf count = 44
\[ \left \{ \int _{{\it \_b}}^{y \left ( x \right ) }\!{{{\it \_a}}^{2}{\frac {1}{\sqrt {-9\,{x}^{4}+4\,{{\it \_a}}^{3}}}}}\,{\rm d}{\it \_a}-{\frac {{x}^{4}}{4}}-{\frac {{x}^{3}}{3}}-x-{\it \_C1}=0 \right \} \]