Integral of $$$3 x^{6} y^{3}$$$ with respect to $$$x$$$

Find $$$\int 3 x^{6} y^{3}\, dx$$$.

Apply the constant multiple rule $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ with $$$c=3 y^{3}$$$ and $$$f{\left(x \right)} = x^{6}$$$:

$${\color{red}{\int{3 x^{6} y^{3} d x}}} = {\color{red}{\left(3 y^{3} \int{x^{6} d x}\right)}}$$

Apply the power rule $$$\int x^{n}\, dx = \frac{x^{n + 1}}{n + 1}$$$ $$$\left(n \neq -1 \right)$$$ with $$$n=6$$$:

$$3 y^{3} {\color{red}{\int{x^{6} d x}}}=3 y^{3} {\color{red}{\frac{x^{1 + 6}}{1 + 6}}}=3 y^{3} {\color{red}{\left(\frac{x^{7}}{7}\right)}}$$

Therefore,

$$\int{3 x^{6} y^{3} d x} = \frac{3 x^{7} y^{3}}{7}$$

Add the constant of integration:

$$\int{3 x^{6} y^{3} d x} = \frac{3 x^{7} y^{3}}{7}+C$$

$$$\int 3 x^{6} y^{3}\, dx = \frac{3 x^{7} y^{3}}{7} + C$$$A