\[ a e^x \sqrt {y(x)}+y''(x)=0 \] ✗ Mathematica : cpu = 20.1348 (sec), leaf count = 0 , could not solve
DSolve[a*E^x*Sqrt[y[x]] + Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 4.166 (sec), leaf count = 104
\[ \left \{ y \left ( x \right ) ={\it ODESolStruc} \left ( {\frac {{\it \_a}}{{{\rm e}^{-2\,\int \!{\it \_b} \left ( {\it \_a} \right ) \,{\rm d}{\it \_a}-2\,{\it \_C1}}}}},[ \left \{ {\frac {\rm d}{{\rm d}{\it \_a}}}{\it \_b} \left ( {\it \_a} \right ) = \left ( {\it \_b} \left ( {\it \_a} \right ) \right ) ^{2} \left ( \sqrt {{\it \_a}}{\it \_b} \left ( {\it \_a} \right ) a+4\,{\it \_b} \left ( {\it \_a} \right ) {\it \_a}+4 \right ) \right \} , \left \{ {\it \_a}=y \left ( x \right ) {{\rm e}^{-2\,x}},{\it \_b} \left ( {\it \_a} \right ) ={\frac {1}{{{\rm e}^{-2\,x}} \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -2\,y \left ( x \right ) \right ) }} \right \} , \left \{ x=\int \!{\it \_b} \left ( {\it \_a} \right ) \,{\rm d}{\it \_a}+{\it \_C1},y \left ( x \right ) ={\frac {{\it \_a}}{{{\rm e}^{-2\,\int \!{\it \_b} \left ( {\it \_a} \right ) \,{\rm d}{\it \_a}-2\,{\it \_C1}}}}} \right \} ] \right ) \right \} \]