\[ y'(x)^2 (-((2 a b-a-b) y(x)+(1-a) b))+a b (y(x)-1) y(x) y''(x)+f(x) (y(x)-1) y(x) y'(x)=0 \] ✓ Mathematica : cpu = 0.140087 (sec), leaf count = 69
\[\left \{\left \{y(x)\to \text {InverseFunction}\left [-a \text {$\#$1}^{\frac {1}{a}} \, _2F_1\left (\frac {1}{a},1-\frac {1}{b};1+\frac {1}{a};\text {$\#$1}\right )\& \right ]\left [\int _1^x\exp \left (-\int _1^{K[3]}\frac {f(K[1])}{a b}dK[1]\right ) c_1dK[3]+c_2\right ]\right \}\right \}\] ✓ Maple : cpu = 0.29 (sec), leaf count = 46
\[ \left \{ {\it \_C1}\,{{\rm e}^{-{\frac {fx}{ab}}}}-{\it \_C2}+\int ^{y \left ( x \right ) }\!{\frac {\sqrt [a]{{\it \_a}}\sqrt [b]{{\it \_a}-1}}{{\it \_a}\, \left ( {\it \_a}-1 \right ) }}{d{\it \_a}}=0 \right \} \]