Integral of $$$- \frac{1}{u}$$$

Find $$$\int \left(- \frac{1}{u}\right)\, du$$$.

Apply the constant multiple rule $$$\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$$$ with $$$c=-1$$$ and $$$f{\left(u \right)} = \frac{1}{u}$$$:

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

The integral of $$$\frac{1}{u}$$$ is $$$\int{\frac{1}{u} d u} = \ln{\left(\left|{u}\right| \right)}$$$:

$$- {\color{red}{\int{\frac{1}{u} d u}}} = - {\color{red}{\ln{\left(\left|{u}\right| \right)}}}$$

Therefore,

$$\int{\left(- \frac{1}{u}\right)d u} = - \ln{\left(\left|{u}\right| \right)}$$

Add the constant of integration:

$$\int{\left(- \frac{1}{u}\right)d u} = - \ln{\left(\left|{u}\right| \right)}+C$$

$$$\int \left(- \frac{1}{u}\right)\, du = - \ln\left(\left|{u}\right|\right) + C$$$A