$$$- 5^{u}$$$の積分

$$$\int \left(- 5^{u}\right)\, du$$$ を求めよ。

定数倍の法則 $$$\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$$$ を、$$$c=-1$$$ と $$$f{\left(u \right)} = 5^{u}$$$ に対して適用する:

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

Apply the exponential rule $$$\int{a^{u} d u} = \frac{a^{u}}{\ln{\left(a \right)}}$$$ with $$$a=5$$$:

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

したがって、

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

積分定数を加える:

$$\int{\left(- 5^{u}\right)d u} = - \frac{5^{u}}{\ln{\left(5 \right)}}+C$$

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