\[ \boxed { a \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}+b{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -y \left ( x \right ) =0} \]
Mathematica: cpu = 0.302538 (sec), leaf count = 116 \[ \left \{\left \{y(x)\to \text {InverseFunction}\left [\frac {\sqrt {4 \text {$\#$1} a+b^2}+b \log \left (\sqrt {4 \text {$\#$1} a+b^2}-b\right )}{2 a}\& \right ]\left [\frac {x}{2 a}+c_1\right ]\right \},\left \{y(x)\to \text {InverseFunction}\left [\frac {\sqrt {4 \text {$\#$1} a+b^2}-b \log \left (\sqrt {4 \text {$\#$1} a+b^2}+b\right )}{2 a}\& \right ]\left [c_1-\frac {x}{2 a}\right ]\right \}\right \} \]
Maple: cpu = 0.858 (sec), leaf count = 197 \[ \left \{ y \left ( x \right ) ={\frac {1}{4\,a}{{\rm e}^{-{\frac {1}{2\, b} \left ( b\ln \left ( {\frac {1}{4\,a}} \right ) +2\,b{\it lambertW} \left ( 2\,{\frac {{{\rm e}^{-1}}}{b\sqrt {{a}^{-1}}}{{\rm e}^{{\frac {x}{b}}}} \left ( {{\rm e}^{{\frac {{\it \_C1}}{b}}}} \right ) ^{-1}} \right ) +2\,{\it \_C1}+2\,b-2\,x \right ) }}} \left ( {{\rm e}^{-{ \frac {1}{2\,b} \left ( b\ln \left ( {\frac {1}{4\,a}} \right ) +2\,b{ \it lambertW} \left ( 2\,{\frac {{{\rm e}^{-1}}}{b\sqrt {{a}^{-1}}}{ {\rm e}^{{\frac {x}{b}}}} \left ( {{\rm e}^{{\frac {{\it \_C1}}{b}}}} \right ) ^{-1}} \right ) +2\,{\it \_C1}+2\,b-2\,x \right ) }}}+2\,b \right ) },y \left ( x \right ) ={\frac {1}{4\,a}{{\rm e}^{{\it RootOf} \left ( b\ln \left ( {\frac { \left ( {{\rm e}^{{\it \_Z}}}+2\,b \right ) ^{2}}{4\,a}} \right ) -2\,{{\rm e}^{{\it \_Z}}}+2\,{\it \_C1}- 2\,b-2\,x \right ) }} \left ( {{\rm e}^{{\it RootOf} \left ( b\ln \left ( {\frac { \left ( {{\rm e}^{{\it \_Z}}}+2\,b \right ) ^{2}}{4\,a} } \right ) -2\,{{\rm e}^{{\it \_Z}}}+2\,{\it \_C1}-2\,b-2\,x \right ) }} +2\,b \right ) } \right \} \]