\[ y'(x)^n-f(x)^n (y(x)-a)^{n+1} (y(x)-b)^{n-1}=0 \] ✓ Mathematica : cpu = 0.125296 (sec), leaf count = 86
\[\left \{\left \{y(x)\to \frac {-b n^n-a (a-b)^n \left (\int _1^x(-1)^{1+\frac {1}{n}} f(K[1])dK[1]+c_1\right ){}^n}{-n^n-(a-b)^n \left (\int _1^x(-1)^{1+\frac {1}{n}} f(K[1])dK[1]+c_1\right ){}^n}\right \}\right \}\] ✓ Maple : cpu = 1.402 (sec), leaf count = 55
\[ \left \{ y \left ( x \right ) ={ \left ( \left ( -{\frac {n}{ \left ( a-b \right ) \left ( \int \!f \left ( x \right ) \,{\rm d}x+{\it \_C1} \right ) }} \right ) ^{n}b-a \right ) \left ( -1+ \left ( -{\frac {n}{ \left ( a-b \right ) \left ( \int \!f \left ( x \right ) \,{\rm d}x+{\it \_C1} \right ) }} \right ) ^{n} \right ) ^{-1}} \right \} \]