Integral of $$$1 - y$$$

Find $$$\int \left(1 - y\right)\, dy$$$.

Integrate term by term:

$${\color{red}{\int{\left(1 - y\right)d y}}} = {\color{red}{\left(\int{1 d y} - \int{y d y}\right)}}$$

Apply the constant rule $$$\int c\, dy = c y$$$ with $$$c=1$$$:

$$- \int{y d y} + {\color{red}{\int{1 d y}}} = - \int{y d y} + {\color{red}{y}}$$

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

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

Therefore,

$$\int{\left(1 - y\right)d y} = - \frac{y^{2}}{2} + y$$

Simplify:

$$\int{\left(1 - y\right)d y} = \frac{y \left(2 - y\right)}{2}$$

Add the constant of integration:

$$\int{\left(1 - y\right)d y} = \frac{y \left(2 - y\right)}{2}+C$$

$$$\int \left(1 - y\right)\, dy = \frac{y \left(2 - y\right)}{2} + C$$$A