\[ \boxed { ay \left ( x \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +b \left ( y \left ( x \right ) \right ) ^{2}+f \left ( x \right ) =0} \]
Mathematica: cpu = 0.121515 (sec), leaf count = 96 \[ \left \{\left \{y(x)\to -e^{-\frac {b x}{a}} \sqrt {2 \int _1^x -\frac {f(K[1]) e^{\frac {2 b K[1]}{a}}}{a} \, dK[1]+c_1}\right \},\left \{y(x)\to e^{-\frac {b x}{a}} \sqrt {2 \int _1^x -\frac {f(K[1]) e^{\frac {2 b K[1]}{a}}}{a} \, dK[1]+c_1}\right \}\right \} \]
Maple: cpu = 0.047 (sec), leaf count = 104 \[ \left \{ y \left ( x \right ) ={\frac {1}{a}\sqrt {-{{\rm e}^{2\,{\frac {bx}{a}}}}a \left ( -{\it \_C1}\,a+2\,\int \! \left ( {{\rm e}^{{\frac { bx}{a}}}} \right ) ^{2}f \left ( x \right ) \,{\rm d}x \right ) } \left ( { {\rm e}^{2\,{\frac {bx}{a}}}} \right ) ^{-1}},y \left ( x \right ) =-{ \frac {1}{a}\sqrt {-{{\rm e}^{2\,{\frac {bx}{a}}}}a \left ( -{\it \_C1} \,a+2\,\int \! \left ( {{\rm e}^{{\frac {bx}{a}}}} \right ) ^{2}f \left ( x \right ) \,{\rm d}x \right ) } \left ( {{\rm e}^{2\,{\frac {bx }{a}}}} \right ) ^{-1}} \right \} \]