Answer
$\displaystyle \frac{1}{2.1}e^{2.1x}+C$
Work Step by Step
$\displaystyle \int e^{2.1x}dx=$
Shortcut formula:
$\displaystyle \qquad\int e^{ax+b}dx=\frac{1}{a}e^{a\mathrm{x}+b}+C$
Apply with $ \left[\begin{array}{l}
a=2.1\\
b=0
\end{array}\right]$
= $\displaystyle \frac{1}{2.1}e^{2.1x}+C$
