Integral of $$$x + e^{x}$$$

Find $$$\int \left(x + e^{x}\right)\, dx$$$.

Integrate term by term:

$${\color{red}{\int{\left(x + e^{x}\right)d x}}} = {\color{red}{\left(\int{x d x} + \int{e^{x} d x}\right)}}$$

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

$$\int{e^{x} d x} + {\color{red}{\int{x d x}}}=\int{e^{x} d x} + {\color{red}{\frac{x^{1 + 1}}{1 + 1}}}=\int{e^{x} d x} + {\color{red}{\left(\frac{x^{2}}{2}\right)}}$$

The integral of the exponential function is $$$\int{e^{x} d x} = e^{x}$$$:

$$\frac{x^{2}}{2} + {\color{red}{\int{e^{x} d x}}} = \frac{x^{2}}{2} + {\color{red}{e^{x}}}$$

Therefore,

$$\int{\left(x + e^{x}\right)d x} = \frac{x^{2}}{2} + e^{x}$$

Add the constant of integration:

$$\int{\left(x + e^{x}\right)d x} = \frac{x^{2}}{2} + e^{x}+C$$

$$$\int \left(x + e^{x}\right)\, dx = \left(\frac{x^{2}}{2} + e^{x}\right) + C$$$A