Integraal van $$$\frac{2}{x - 3}$$$

Bepaal $$$\int \frac{2}{x - 3}\, dx$$$.

Pas de constante-veelvoudregel $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ toe met $$$c=2$$$ en $$$f{\left(x \right)} = \frac{1}{x - 3}$$$:

$${\color{red}{\int{\frac{2}{x - 3} d x}}} = {\color{red}{\left(2 \int{\frac{1}{x - 3} d x}\right)}}$$

Zij $$$u=x - 3$$$.

Dan $$$du=\left(x - 3\right)^{\prime }dx = 1 dx$$$ (de stappen zijn te zien »), en dan geldt dat $$$dx = du$$$.

De integraal kan worden herschreven als

$$2 {\color{red}{\int{\frac{1}{x - 3} d x}}} = 2 {\color{red}{\int{\frac{1}{u} d u}}}$$

De integraal van $$$\frac{1}{u}$$$ is $$$\int{\frac{1}{u} d u} = \ln{\left(\left|{u}\right| \right)}$$$:

$$2 {\color{red}{\int{\frac{1}{u} d u}}} = 2 {\color{red}{\ln{\left(\left|{u}\right| \right)}}}$$

We herinneren eraan dat $$$u=x - 3$$$:

$$2 \ln{\left(\left|{{\color{red}{u}}}\right| \right)} = 2 \ln{\left(\left|{{\color{red}{\left(x - 3\right)}}}\right| \right)}$$

Dus,

$$\int{\frac{2}{x - 3} d x} = 2 \ln{\left(\left|{x - 3}\right| \right)}$$

Voeg de integratieconstante toe:

$$\int{\frac{2}{x - 3} d x} = 2 \ln{\left(\left|{x - 3}\right| \right)}+C$$

$$$\int \frac{2}{x - 3}\, dx = 2 \ln\left(\left|{x - 3}\right|\right) + C$$$A