Consider the integral $\displaystyle \int\frac{{{e}^{{y}}}}{{{e}^{{y}}+{3}}}\ {\left.{d}{y}\right.}$:

This can be transformed into a basic integral by letting

$\displaystyle {u}=$ Preview Question 6 Part 1 of 3   and

$\displaystyle {d}{u}=$ $\displaystyle {\left.{d}{y}\right.}$ Preview Question 6 Part 2 of 3  

After performing the substitution, you obtain the integral

$\displaystyle \int$ $\displaystyle {d}{u}$ Preview Question 6 Part 3 of 3