Integral of $$$e^{3}$$$

Apply the power rule $$$\int e^{n}\, de = \frac{e^{n + 1}}{n + 1}$$$ $$$\left(n \neq -1 \right)$$$ with $$$n=3$$$:

$${\color{red}{\int{e^{3} d e}}}={\color{red}{\frac{e^{1 + 3}}{1 + 3}}}={\color{red}{\left(\frac{e^{4}}{4}\right)}}$$

Therefore,

$$\int{e^{3} d e} = \frac{e^{4}}{4}$$

Add the constant of integration:

$$\int{e^{3} d e} = \frac{e^{4}}{4}+C$$

$$$\int e^{3}\, de = \frac{e^{4}}{4} + C$$$A