Integral de $$$\sec^{2}{\left(2 x \right)}$$$

Encontre $$$\int \sec^{2}{\left(2 x \right)}\, dx$$$.

Seja $$$u=2 x$$$.

Então $$$du=\left(2 x\right)^{\prime }dx = 2 dx$$$ (veja os passos »), e obtemos $$$dx = \frac{du}{2}$$$.

Assim,

$${\color{red}{\int{\sec^{2}{\left(2 x \right)} d x}}} = {\color{red}{\int{\frac{\sec^{2}{\left(u \right)}}{2} d u}}}$$

Aplique a regra do múltiplo constante $$$\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$$$ usando $$$c=\frac{1}{2}$$$ e $$$f{\left(u \right)} = \sec^{2}{\left(u \right)}$$$:

$${\color{red}{\int{\frac{\sec^{2}{\left(u \right)}}{2} d u}}} = {\color{red}{\left(\frac{\int{\sec^{2}{\left(u \right)} d u}}{2}\right)}}$$

A integral de $$$\sec^{2}{\left(u \right)}$$$ é $$$\int{\sec^{2}{\left(u \right)} d u} = \tan{\left(u \right)}$$$:

$$\frac{{\color{red}{\int{\sec^{2}{\left(u \right)} d u}}}}{2} = \frac{{\color{red}{\tan{\left(u \right)}}}}{2}$$

Recorde que $$$u=2 x$$$:

$$\frac{\tan{\left({\color{red}{u}} \right)}}{2} = \frac{\tan{\left({\color{red}{\left(2 x\right)}} \right)}}{2}$$

Portanto,

$$\int{\sec^{2}{\left(2 x \right)} d x} = \frac{\tan{\left(2 x \right)}}{2}$$

Adicione a constante de integração:

$$\int{\sec^{2}{\left(2 x \right)} d x} = \frac{\tan{\left(2 x \right)}}{2}+C$$

$$$\int \sec^{2}{\left(2 x \right)}\, dx = \frac{\tan{\left(2 x \right)}}{2} + C$$$A