Integral de $$$37000 e^{- \frac{9 t}{100}}$$$

Encontre $$$\int 37000 e^{- \frac{9 t}{100}}\, dt$$$.

Aplique a regra do múltiplo constante $$$\int c f{\left(t \right)}\, dt = c \int f{\left(t \right)}\, dt$$$ usando $$$c=37000$$$ e $$$f{\left(t \right)} = e^{- \frac{9 t}{100}}$$$:

$${\color{red}{\int{37000 e^{- \frac{9 t}{100}} d t}}} = {\color{red}{\left(37000 \int{e^{- \frac{9 t}{100}} d t}\right)}}$$

Seja $$$u=- \frac{9 t}{100}$$$.

Então $$$du=\left(- \frac{9 t}{100}\right)^{\prime }dt = - \frac{9 dt}{100}$$$ (veja os passos »), e obtemos $$$dt = - \frac{100 du}{9}$$$.

A integral pode ser reescrita como

$$37000 {\color{red}{\int{e^{- \frac{9 t}{100}} d t}}} = 37000 {\color{red}{\int{\left(- \frac{100 e^{u}}{9}\right)d u}}}$$

Aplique a regra do múltiplo constante $$$\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$$$ usando $$$c=- \frac{100}{9}$$$ e $$$f{\left(u \right)} = e^{u}$$$:

$$37000 {\color{red}{\int{\left(- \frac{100 e^{u}}{9}\right)d u}}} = 37000 {\color{red}{\left(- \frac{100 \int{e^{u} d u}}{9}\right)}}$$

A integral da função exponencial é $$$\int{e^{u} d u} = e^{u}$$$:

$$- \frac{3700000 {\color{red}{\int{e^{u} d u}}}}{9} = - \frac{3700000 {\color{red}{e^{u}}}}{9}$$

Recorde que $$$u=- \frac{9 t}{100}$$$:

$$- \frac{3700000 e^{{\color{red}{u}}}}{9} = - \frac{3700000 e^{{\color{red}{\left(- \frac{9 t}{100}\right)}}}}{9}$$

Portanto,

$$\int{37000 e^{- \frac{9 t}{100}} d t} = - \frac{3700000 e^{- \frac{9 t}{100}}}{9}$$

Adicione a constante de integração:

$$\int{37000 e^{- \frac{9 t}{100}} d t} = - \frac{3700000 e^{- \frac{9 t}{100}}}{9}+C$$

$$$\int 37000 e^{- \frac{9 t}{100}}\, dt = - \frac{3700000 e^{- \frac{9 t}{100}}}{9} + C$$$A