$$$\frac{\ln^{5}\left(u^{2}\right)}{u}$$$ 的积分

求$$$\int \frac{\ln^{5}\left(u^{2}\right)}{u}\, du$$$。

输入已重写为：$$$\int{\frac{\ln{\left(u^{2} \right)}^{5}}{u} d u}=\int{\frac{32 \ln{\left(u \right)}^{5}}{u} d u}$$$。

对 $$$c=32$$$ 和 $$$f{\left(u \right)} = \frac{\ln{\left(u \right)}^{5}}{u}$$$ 应用常数倍法则 $$$\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$$$：

$${\color{red}{\int{\frac{32 \ln{\left(u \right)}^{5}}{u} d u}}} = {\color{red}{\left(32 \int{\frac{\ln{\left(u \right)}^{5}}{u} d u}\right)}}$$

设$$$v=\ln{\left(u \right)}$$$。

则$$$dv=\left(\ln{\left(u \right)}\right)^{\prime }du = \frac{du}{u}$$$ (步骤见»)，并有$$$\frac{du}{u} = dv$$$。

该积分可以改写为

$$32 {\color{red}{\int{\frac{\ln{\left(u \right)}^{5}}{u} d u}}} = 32 {\color{red}{\int{v^{5} d v}}}$$

应用幂法则 $$$\int v^{n}\, dv = \frac{v^{n + 1}}{n + 1}$$$ $$$\left(n \neq -1 \right)$$$，其中 $$$n=5$$$：

$$32 {\color{red}{\int{v^{5} d v}}}=32 {\color{red}{\frac{v^{1 + 5}}{1 + 5}}}=32 {\color{red}{\left(\frac{v^{6}}{6}\right)}}$$

回忆一下 $$$v=\ln{\left(u \right)}$$$:

$$\frac{16 {\color{red}{v}}^{6}}{3} = \frac{16 {\color{red}{\ln{\left(u \right)}}}^{6}}{3}$$

因此，

$$\int{\frac{32 \ln{\left(u \right)}^{5}}{u} d u} = \frac{16 \ln{\left(u \right)}^{6}}{3}$$

加上积分常数：

$$\int{\frac{32 \ln{\left(u \right)}^{5}}{u} d u} = \frac{16 \ln{\left(u \right)}^{6}}{3}+C$$

$$$\int \frac{\ln^{5}\left(u^{2}\right)}{u}\, du = \frac{16 \ln^{6}\left(u\right)}{3} + C$$$A