Integral of $$$x^{3}$$$

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

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

Therefore,

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

Add the constant of integration:

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

$$$\int x^{3}\, dx = \frac{x^{4}}{4} + C$$$A