$$$b^{x - 1}$$$ 关于$$$x$$$的积分

求$$$\int b^{x - 1}\, dx$$$。

设$$$u=x - 1$$$。

则$$$du=\left(x - 1\right)^{\prime }dx = 1 dx$$$ (步骤见»)，并有$$$dx = du$$$。

积分变为

$${\color{red}{\int{b^{x - 1} d x}}} = {\color{red}{\int{b^{u} d u}}}$$

Apply the exponential rule $$$\int{a^{u} d u} = \frac{a^{u}}{\ln{\left(a \right)}}$$$ with $$$a=b$$$:

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

回忆一下 $$$u=x - 1$$$:

$$\frac{b^{{\color{red}{u}}}}{\ln{\left(b \right)}} = \frac{b^{{\color{red}{\left(x - 1\right)}}}}{\ln{\left(b \right)}}$$

因此，

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

加上积分常数：

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

$$$\int b^{x - 1}\, dx = \frac{b^{x - 1}}{\ln\left(b\right)} + C$$$A