\[ a x+y(x) y'(x)^2+y(x)^2 y''(x)=0 \] ✗ Mathematica : cpu = 22.0149 (sec), leaf count = 0 , could not solve
DSolve[a*x + y[x]*Derivative[1][y][x]^2 + y[x]^2*Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 3.522 (sec), leaf count = 117
\[ \left \{ \ln \left ( x \right ) -{\frac {\sqrt {3}}{6}\int ^{{\frac {y \left ( x \right ) }{x}}}\!{\frac {1}{{{\it \_g}}^{3}+a} \left ( 3\,{{\it \_g}}^{2}\sqrt [3]{{\frac {a}{{{\it \_g}}^{3}}}}\tan \left ( {\it RootOf} \left ( -2\,\sqrt {3}{\it \_Z}+\ln \left ( {\frac { \left ( \tan \left ( {\it \_Z} \right ) \right ) ^{2}+1}{ \left ( \tan \left ( {\it \_Z} \right ) \right ) ^{2}+2\,\sqrt {3}\tan \left ( {\it \_Z} \right ) +3}} \right ) +6\,{\it \_C1}+6\,\int \!{\frac {{{\it \_g}}^{2}}{{{\it \_g}}^{3}+a} \left ( {\frac {a}{{{\it \_g}}^{3}}} \right ) ^{2/3}}\,{\rm d}{\it \_g} \right ) \right ) +{{\it \_g}}^{2}\sqrt {3} \left ( \sqrt [3]{{\frac {a}{{{\it \_g}}^{3}}}}-2 \right ) \right ) }{d{\it \_g}}}-{\it \_C2}=0 \right \} \]