Question

Evaluate :

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

Answer 1

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

Let $e^x+1=t$

$e^{x}dx=dt$

Therefore,

$I=\int \frac{dt}{t}$

$I=\log t+C$

$I=\log (e^x+1)+C$