\[ \boxed { ay \left ( x \right ) \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}+ \left ( 2\,x-b \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -y \left ( x \right ) =0} \]
Mathematica: cpu = 0.304539 (sec), leaf count = 146 \[ \left \{\left \{y(x)\to -\frac {e^{\frac {c_1}{2}} \sqrt {2 b+e^{c_1}-4 x}}{2 \sqrt {a}}\right \},\left \{y(x)\to \frac {e^{\frac {c_1}{2}} \sqrt {2 b+e^{c_1}-4 x}}{2 \sqrt {a}}\right \},\left \{y(x)\to -\sqrt {2} e^{\frac {c_1}{2}} \sqrt {2 a e^{c_1}-b+2 x}\right \},\left \{y(x)\to \sqrt {2} e^{\frac {c_1}{2}} \sqrt {2 a e^{c_1}-b+2 x}\right \}\right \} \]
Maple: cpu = 0.858 (sec), leaf count = 929 \[ \left \{ \int _{{\it \_b}}^{x}\!2\,{\frac {-2\,{\it \_a}+b+\sqrt {4\,a \left ( y \left ( x \right ) \right ) ^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}}{4\,a \left ( y \left ( x \right ) \right ) ^{2}+\sqrt { 4\,a \left ( y \left ( x \right ) \right ) ^{2}+4\,{{\it \_a}}^{2}-4\,{ \it \_a}\,b+{b}^{2}}b-2\,\sqrt {4\,a \left ( y \left ( x \right ) \right ) ^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}{\it \_a}+{b} ^{2}-4\,{\it \_a}\,b+4\,{{\it \_a}}^{2}}}\,{\rm d}{\it \_a}+\int ^{y \left ( x \right ) }\!-4\,{\frac {a{\it \_f}}{4\,a{{\it \_f}}^{2}+ \sqrt {4\,a{{\it \_f}}^{2}+{b}^{2}-4\,bx+4\,{x}^{2}}b-2\,\sqrt {4\,a{{ \it \_f}}^{2}+{b}^{2}-4\,bx+4\,{x}^{2}}x+{b}^{2}-4\,bx+4\,{x}^{2}}}- \int _{{\it \_b}}^{x}\!8\,{\frac {a{\it \_f}}{\sqrt {4\,a{{\it \_f}}^{2 }+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}} \left ( 4\,a{{\it \_f}}^{ 2}+\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{ 2}}b-2\,\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+ {b}^{2}}{\it \_a}+{b}^{2}-4\,{\it \_a}\,b+4\,{{\it \_a}}^{2} \right ) } }-2\,{\frac {-2\,{\it \_a}+b+\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}} ^{2}-4\,{\it \_a}\,b+{b}^{2}}}{ \left ( 4\,a{{\it \_f}}^{2}+\sqrt {4\,a {{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}b-2\,\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}{\it \_a}+{b}^{2}-4\,{\it \_a}\,b+4\,{{\it \_a}}^{2} \right ) ^{2}} \left ( 8 \,a{\it \_f}+4\,{\frac {ba{\it \_f}}{\sqrt {4\,a{{\it \_f}}^{2}+4\,{{ \it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}}}-8\,{\frac {{\it \_a}\,a{\it \_f}}{\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b }^{2}}}} \right ) }\,{\rm d}{\it \_a}{d{\it \_f}}+{\it \_C1}=0,\int _{{ \it \_b}}^{x}\!2\,{\frac {2\,{\it \_a}-b+\sqrt {4\,a \left ( y \left ( x \right ) \right ) ^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}}{-4 \,a \left ( y \left ( x \right ) \right ) ^{2}+\sqrt {4\,a \left ( y \left ( x \right ) \right ) ^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b} ^{2}}b-2\,\sqrt {4\,a \left ( y \left ( x \right ) \right ) ^{2}+4\,{{ \it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}{\it \_a}-{b}^{2}+4\,{\it \_a}\, b-4\,{{\it \_a}}^{2}}}\,{\rm d}{\it \_a}+\int ^{y \left ( x \right ) }\! 4\,{\frac {a{\it \_f}}{-4\,a{{\it \_f}}^{2}+\sqrt {4\,a{{\it \_f}}^{2} +{b}^{2}-4\,bx+4\,{x}^{2}}b-2\,\sqrt {4\,a{{\it \_f}}^{2}+{b}^{2}-4\,b x+4\,{x}^{2}}x-{b}^{2}+4\,bx-4\,{x}^{2}}}-\int _{{\it \_b}}^{x}\!8\,{ \frac {a{\it \_f}}{\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{ \it \_a}\,b+{b}^{2}} \left ( -4\,a{{\it \_f}}^{2}+\sqrt {4\,a{{\it \_f} }^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}b-2\,\sqrt {4\,a{{ \it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}{\it \_a}-{b} ^{2}+4\,{\it \_a}\,b-4\,{{\it \_a}}^{2} \right ) }}-2\,{\frac {2\,{\it \_a}-b+\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{ b}^{2}}}{ \left ( -4\,a{{\it \_f}}^{2}+\sqrt {4\,a{{\it \_f}}^{2}+4\,{{ \it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}b-2\,\sqrt {4\,a{{\it \_f}}^{2}+ 4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}{\it \_a}-{b}^{2}+4\,{\it \_a}\,b-4\,{{\it \_a}}^{2} \right ) ^{2}} \left ( -8\,a{\it \_f}+4\,{ \frac {ba{\it \_f}}{\sqrt {4\,a{{\it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{ \it \_a}\,b+{b}^{2}}}}-8\,{\frac {{\it \_a}\,a{\it \_f}}{\sqrt {4\,a{{ \it \_f}}^{2}+4\,{{\it \_a}}^{2}-4\,{\it \_a}\,b+{b}^{2}}}} \right ) } \,{\rm d}{\it \_a}{d{\it \_f}}+{\it \_C1}=0,y \left ( x \right ) =-{ \frac {-2\,x+b}{2}{\frac {1}{\sqrt {-a}}}},y \left ( x \right ) ={\frac {-2\,x+b}{2}{\frac {1}{\sqrt {-a}}}} \right \} \]