\[ y(x) y''(x)-a x=0 \] ✗ Mathematica : cpu = 20.8141 (sec), leaf count = 0 , could not solve
DSolve[-(a*x) + y[x]*Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 1.84 (sec), leaf count = 103
\[\left \{y \left (x \right ) = \mathit {ODESolStruc} \left (\textit {\_a} \left ({\mathrm e}^{c_{1}+\int \textit {\_}b\left (\textit {\_a} \right )d \textit {\_a}}\right )^{\frac {3}{2}}, \left [\left \{\frac {d}{d \textit {\_a}}\mathrm {\_}\mathrm {b}\left (\textit {\_a} \right )=\frac {\left (3 \textit {\_a}^{2}-4 a \right ) \textit {\_}b\left (\textit {\_a} \right )^{3}}{4 \textit {\_a}}+2 \textit {\_}b\left (\textit {\_a} \right )^{2}\right \}, \left \{\textit {\_a} =\frac {y \left (x \right )}{x^{\frac {3}{2}}}, \textit {\_}b\left (\textit {\_a} \right )=-\frac {2 x^{\frac {3}{2}}}{-2 x \left (\frac {d}{d x}y \left (x \right )\right )+3 y \left (x \right )}\right \}, \left \{x ={\mathrm e}^{c_{1}+\int \textit {\_}b\left (\textit {\_a} \right )d \textit {\_a}}, y \left (x \right )=\textit {\_a} \left ({\mathrm e}^{c_{1}+\int \textit {\_}b\left (\textit {\_a} \right )d \textit {\_a}}\right )^{\frac {3}{2}}\right \}\right ]\right )\right \}\]