\[ y'(x)-x^{a-1} y(x)^{1-b} f\left (\frac {x^a}{a}+\frac {y(x)^b}{b}\right )=0 \] ✓ Mathematica : cpu = 0.314192 (sec), leaf count = 238
DSolve[-(x^(-1 + a)*f[x^a/a + y[x]^b/b]*y[x]^(1 - b)) + Derivative[1][y][x] == 0,y[x],x]
\[\text {Solve}\left [\int _1^{y(x)}\left (-\frac {K[2]^{b-1}}{f\left (\frac {x^a}{a}+\frac {K[2]^b}{b}\right )+1}-\int _1^x\left (\frac {K[1]^{a-1} K[2]^{b-1} f'\left (\frac {K[1]^a}{a}+\frac {K[2]^b}{b}\right )}{f\left (\frac {K[1]^a}{a}+\frac {K[2]^b}{b}\right )+1}-\frac {f\left (\frac {K[1]^a}{a}+\frac {K[2]^b}{b}\right ) K[1]^{a-1} K[2]^{b-1} f'\left (\frac {K[1]^a}{a}+\frac {K[2]^b}{b}\right )}{\left (f\left (\frac {K[1]^a}{a}+\frac {K[2]^b}{b}\right )+1\right )^2}\right )dK[1]\right )dK[2]+\int _1^x\frac {f\left (\frac {K[1]^a}{a}+\frac {y(x)^b}{b}\right ) K[1]^{a-1}}{f\left (\frac {K[1]^a}{a}+\frac {y(x)^b}{b}\right )+1}dK[1]=c_1,y(x)\right ]\] ✓ Maple : cpu = 0.368 (sec), leaf count = 153
dsolve(diff(y(x),x)-x^(a-1)*y(x)^(1-b)*f(x^a/a+y(x)^b/b) = 0,y(x))
\[y \left (x \right ) = \left (-\frac {x^{a} b -\operatorname {RootOf}\left (\left (\int _{}^{\textit {\_Z}}\frac {1}{-\left (\left (-b +\textit {\_a} \right )^{\frac {1}{b}}\right )^{-b} f \left (\frac {\left (a^{\frac {1}{a}}\right )^{a} b +\left (\left (-b +\textit {\_a} \right )^{\frac {1}{b}}\right )^{b} a}{a b}\right ) \left (a^{\frac {1}{a}}\right )^{a} b +\left (\left (-b +\textit {\_a} \right )^{\frac {1}{b}}\right )^{-b} f \left (\frac {\left (a^{\frac {1}{a}}\right )^{a} b +\left (\left (-b +\textit {\_a} \right )^{\frac {1}{b}}\right )^{b} a}{a b}\right ) \left (a^{\frac {1}{a}}\right )^{a} \textit {\_a} +a}d \textit {\_a} \right ) a^{2}+c_{1} a b -x^{a} b \right ) a}{a}\right )^{\frac {1}{b}}\]