Perform the indicated integrations.

$\displaystyle\int\frac{e^x}{e^x + 1} \hbox{d} x$ = . $\displaystyle\int\frac{e^x}{e^{x + 1}} \hbox{d} x$ = . $\displaystyle\int\frac{e^{x+1}}{e^x + 1} \hbox{d} x$ = .