Integral of $$$c + f^{2} x^{2}$$$ with respect to $$$x$$$

Find $$$\int \left(c + f^{2} x^{2}\right)\, dx$$$.

Integrate term by term:

$${\color{red}{\int{\left(c + f^{2} x^{2}\right)d x}}} = {\color{red}{\left(\int{c d x} + \int{f^{2} x^{2} d x}\right)}}$$

Apply the constant rule $$$\int c\, dx = c x$$$ with $$$c=c$$$:

$$\int{f^{2} x^{2} d x} + {\color{red}{\int{c d x}}} = \int{f^{2} x^{2} d x} + {\color{red}{c x}}$$

Apply the constant multiple rule $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ with $$$c=f^{2}$$$ and $$$f{\left(x \right)} = x^{2}$$$:

$$c x + {\color{red}{\int{f^{2} x^{2} d x}}} = c x + {\color{red}{f^{2} \int{x^{2} d x}}}$$

Apply the power rule $$$\int x^{n}\, dx = \frac{x^{n + 1}}{n + 1}$$$ $$$\left(n \neq -1 \right)$$$ with $$$n=2$$$:

$$c x + f^{2} {\color{red}{\int{x^{2} d x}}}=c x + f^{2} {\color{red}{\frac{x^{1 + 2}}{1 + 2}}}=c x + f^{2} {\color{red}{\left(\frac{x^{3}}{3}\right)}}$$

Therefore,

$$\int{\left(c + f^{2} x^{2}\right)d x} = c x + \frac{f^{2} x^{3}}{3}$$

Simplify:

$$\int{\left(c + f^{2} x^{2}\right)d x} = x \left(c + \frac{f^{2} x^{2}}{3}\right)$$

Add the constant of integration:

$$\int{\left(c + f^{2} x^{2}\right)d x} = x \left(c + \frac{f^{2} x^{2}}{3}\right)+C$$

$$$\int \left(c + f^{2} x^{2}\right)\, dx = x \left(c + \frac{f^{2} x^{2}}{3}\right) + C$$$A