\[ 9 y'(x)^4+8 y''(x)=0 \] ✓ Mathematica : cpu = 0.0644628 (sec), leaf count = 92
\[\left \{\left \{y(x)\to c_2-\frac {1}{3} \sqrt [3]{-\frac {1}{3}} (9 x-8 c_1){}^{2/3}\right \},\left \{y(x)\to \frac {(9 x-8 c_1){}^{2/3}}{3 \sqrt [3]{3}}+c_2\right \},\left \{y(x)\to \frac {(-1)^{2/3} (9 x-8 c_1){}^{2/3}}{3 \sqrt [3]{3}}+c_2\right \}\right \}\] ✓ Maple : cpu = 0.307 (sec), leaf count = 51
\[ \left \{ y \left ( x \right ) = \left ( x+{\it \_C1} \right ) ^{{\frac {2}{3}}}+{\it \_C2},y \left ( x \right ) ={\frac {-1+i\sqrt {3}}{2} \left ( x+{\it \_C1} \right ) ^{{\frac {2}{3}}}}+{\it \_C2},y \left ( x \right ) =-{\frac {1+i\sqrt {3}}{2} \left ( x+{\it \_C1} \right ) ^{{\frac {2}{3}}}}+{\it \_C2} \right \} \]