Question

$\int \frac{e^{x}dx}{e^x+1}$

Answer 1

$\int \frac{e^x}{e^x+1}dx$

Let $e^x+1=z⟹e^{x}dx=dz$

$\int \frac{1}{z}dz$

$=\ln |z|+c$

$=\ln |e^x+1|+c$