# How do you evaluate the integral int 2^x/(2^x+1)?

$\ln \frac{{2}^{x} + 1}{\ln} 2 + C$
Since $\frac{d}{\mathrm{dx}} \left({2}^{x} + 1\right) = {2}^{x} \ln 2$, we have
$\int {2}^{x} / \left({2}^{x} + 1\right) \mathrm{dx} = \frac{1}{\ln} 2 \int \frac{d \left({2}^{x} + 1\right)}{{2}^{x} + 1} = \ln \frac{{2}^{x} + 1}{\ln} 2 + C$