\[ a y'(x)^2+b y(x)+y''(x)=0 \] ✓ Mathematica : cpu = 0.579576 (sec), leaf count = 104
\[\left \{\left \{y(x)\to \text {InverseFunction}\left [\int _1^{\text {$\#$1}}-\frac {\sqrt {2} a}{\sqrt {2 e^{-2 a K[1]} c_1 a^2-2 b K[1] a+b}}dK[1]\& \right ][c_2+x]\right \},\left \{y(x)\to \text {InverseFunction}\left [\int _1^{\text {$\#$1}}\frac {\sqrt {2} a}{\sqrt {2 e^{-2 a K[2]} c_1 a^2-2 b K[2] a+b}}dK[2]\& \right ][c_2+x]\right \}\right \}\] ✓ Maple : cpu = 0.154 (sec), leaf count = 79
\[ \left \{ \int ^{y \left ( x \right ) }\!-2\,{\frac {a}{\sqrt {4\,{{\rm e}^{-2\,a{\it \_a}}}{\it \_C1}\,{a}^{2}-4\,b{\it \_a}\,a+2\,b}}}{d{\it \_a}}-x-{\it \_C2}=0,\int ^{y \left ( x \right ) }\!2\,{\frac {a}{\sqrt {4\,{{\rm e}^{-2\,a{\it \_a}}}{\it \_C1}\,{a}^{2}-4\,b{\it \_a}\,a+2\,b}}}{d{\it \_a}}-x-{\it \_C2}=0 \right \} \]