\[ y'(x)=\frac {e^{-2 b x} y(x)^3}{e^{-b x} y(x)+1} \] ✓ Mathematica : cpu = 1.15861 (sec), leaf count = 90
\[\text {Solve}\left [\frac {\log (y(x))}{b}+\frac {1}{2} \left (-\frac {\log \left (y(x)^2-b e^{b x} \left (e^{b x}+y(x)\right )\right )}{b}+\frac {2 \tanh ^{-1}\left (\frac {\sqrt {\frac {b}{b+4}} \left (2 e^{b x}+y(x)\right )}{y(x)}\right )}{\sqrt {b} \sqrt {b+4}}+2 x\right )=c_1,y(x)\right ]\] ✓ Maple : cpu = 0.303 (sec), leaf count = 82
\[\left \{b x -\frac {b \arctanh \left (\frac {-2 \,{\mathrm e}^{-b x} y \left (x \right )+b}{\sqrt {b^{2}+4 b}}\right )}{\sqrt {b^{2}+4 b}}-c_{1}+\ln \left ({\mathrm e}^{-b x} y \left (x \right )\right )-\frac {\ln \left (-b \,{\mathrm e}^{-b x} y \left (x \right )+{\mathrm e}^{-2 b x} y \left (x \right )^{2}-b \right )}{2} = 0\right \}\]