\[ -a x-b+y(x) y'(x)^2+y(x)^2 y''(x)=0 \] ✗ Mathematica : cpu = 20.2972 (sec), leaf count = 0 , could not solve
DSolve[-b - a*x + y[x]*Derivative[1][y][x]^2 + y[x]^2*Derivative[2][y][x] == 0, y[x], x]
✓ Maple : cpu = 3.84 (sec), leaf count = 156
\[ \left \{ {\frac {b\ln \left ( ax+b \right ) }{a}}-{\frac {\sqrt {3}}{6}\int ^{{\frac {y \left ( x \right ) }{ax+b}}}\!-2\,{\frac {{{\it \_g}}^{2}b}{{{\it \_g}}^{3}{a}^{2}-1} \left ( -3/2\,b\sqrt [3]{-{\frac {a}{{{\it \_g}}^{3}{b}^{3}}}}\tan \left ( {\it RootOf} \left ( 6\,{b}^{2}\int \!{\frac {{{\it \_g}}^{2}}{{{\it \_g}}^{3}{a}^{2}-1} \left ( -{\frac {a}{{{\it \_g}}^{3}{b}^{3}}} \right ) ^{2/3}}\,{\rm d}{\it \_g}-2\,\sqrt {3}{\it \_Z}+\ln \left ( {\frac { \left ( \tan \left ( {\it \_Z} \right ) \right ) ^{2}+1}{ \left ( \tan \left ( {\it \_Z} \right ) \right ) ^{2}+2\,\sqrt {3}\tan \left ( {\it \_Z} \right ) +3}} \right ) +6\,{\it \_C1} \right ) \right ) +\sqrt {3} \left ( -1/2\,b\sqrt [3]{-{\frac {a}{{{\it \_g}}^{3}{b}^{3}}}}+a \right ) \right ) }{d{\it \_g}}}-{\it \_C2}=0 \right \} \]