\[ y''(x)-6 y(x)^2+4 y(x)=0 \] ✓ Mathematica : cpu = 0.521527 (sec), leaf count = 200
\[\left \{\left \{y(x)\to \left (\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,2\right ]-\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,3\right ]\right ) \text {sn}\left (\sqrt {-\left (x+c_2\right ){}^2 \left (\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,2\right ]+2 \text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,3\right ]-1\right )}|\frac {\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,2\right ]-\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,3\right ]}{\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,1\right ]-\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,3\right ]}\right ){}^2+\text {Root}\left [4 \text {$\#$1}^3-4 \text {$\#$1}^2+c_1\& ,3\right ]\right \}\right \}\]
✓ Maple : cpu = 0.314 (sec), leaf count = 59
\[ \left \{ \int ^{y \left ( x \right ) }\!{\frac {1}{\sqrt {4\,{{\it \_a}}^{3}-4\,{{\it \_a}}^{2}+{\it \_C1}}}}{d{\it \_a}}-x-{\it \_C2}=0,\int ^{y \left ( x \right ) }\!-{\frac {1}{\sqrt {4\,{{\it \_a}}^{3}-4\,{{\it \_a}}^{2}+{\it \_C1}}}}{d{\it \_a}}-x-{\it \_C2}=0 \right \} \]