\[ 40 y^{(3)}(x)^3+9 y^{(5)}(x) y''(x)^2-45 y^{(4)}(x) y^{(3)}(x) y''(x)=0 \] ✓ Mathematica : cpu = 0.141571 (sec), leaf count = 43
\[\left \{\left \{y(x)\to c_5 x-\frac {4 \sqrt {x (c_3 x+c_2)+c_1}}{c_2{}^2-4 c_1 c_3}+c_4\right \}\right \}\] ✓ Maple : cpu = 1.053 (sec), leaf count = 110
\[\left \{y \left (x \right ) = c_{4} x +c_{5}+\int \int \RootOf \left (c_{3}+x -\left (\int _{}^{\textit {\_Z}}\frac {1}{\RootOf \left (20 c_{2}+\int _{}^{\textit {\_Z}}\left ({\mathrm e}^{\RootOf \left (81 \textit {\_k}^{2} {\mathrm e}^{\textit {\_Z}}+162 c_{1} {\mathrm e}^{\textit {\_Z}}-20 \textit {\_Z} \,{\mathrm e}^{\textit {\_Z}}+2187 \textit {\_k}^{2}+20 \,{\mathrm e}^{\textit {\_Z}} \ln \left ({\mathrm e}^{\textit {\_Z}}+27\right )+4374 c_{1}-540 \textit {\_Z} -40 \ln \left (2\right ) {\mathrm e}^{\textit {\_Z}}-20 \ln \left (5\right ) {\mathrm e}^{\textit {\_Z}}+540 \ln \left ({\mathrm e}^{\textit {\_Z}}+27\right )-1080 \ln \left (2\right )-540 \ln \left (5\right )-540\right )}+27\right ) \textit {\_k} d \textit {\_k} -20 \ln \left (\textit {\_f} \right )\right )}d \textit {\_f} \right )\right )d x d x\right \}\]