$\underset{n}{lim}\frac{3}{n}{\displaystyle \underset{i=0}{\overset{n}{}}}{e}^{(\frac{3i}{n}-6)}=$

${\displaystyle \underset{0}{\overset{1}{}}}{e}^{x-4}dx$

${\displaystyle \underset{-2}{\overset{1}{}}}{e}^{(x-4)}dx$

${\displaystyle \underset{0}{\overset{3}{}}}{e}^{x-4}dx$

${\displaystyle \underset{-2}{\overset{1}{}}}{e}^{x}dx$