Integral de $$$\ln\left(x\right)$$$

Halla $$$\int \ln\left(x\right)\, dx$$$.

Para la integral $$$\int{\ln{\left(x \right)} d x}$$$, utiliza la integración por partes $$$\int \operatorname{u} \operatorname{dv} = \operatorname{u}\operatorname{v} - \int \operatorname{v} \operatorname{du}$$$.

Sean $$$\operatorname{u}=\ln{\left(x \right)}$$$ y $$$\operatorname{dv}=dx$$$.

Entonces $$$\operatorname{du}=\left(\ln{\left(x \right)}\right)^{\prime }dx=\frac{dx}{x}$$$ (los pasos pueden verse ») y $$$\operatorname{v}=\int{1 d x}=x$$$ (los pasos pueden verse »).

Por lo tanto,

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

Aplica la regla de la constante $$$\int c\, dx = c x$$$ con $$$c=1$$$:

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

Por lo tanto,

$$\int{\ln{\left(x \right)} d x} = x \ln{\left(x \right)} - x$$

Simplificar:

$$\int{\ln{\left(x \right)} d x} = x \left(\ln{\left(x \right)} - 1\right)$$

Añade la constante de integración:

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

$$$\int \ln\left(x\right)\, dx = x \left(\ln\left(x\right) - 1\right) + C$$$A