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

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

Terapkan aturan pengali konstanta $$$\int c f{\left(x \right)}\, dx = c \int f{\left(x \right)}\, dx$$$ dengan $$$c=\frac{1}{2}$$$ dan $$$f{\left(x \right)} = \sec^{2}{\left(\frac{x}{2} \right)}$$$:

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

Misalkan $$$u=\frac{x}{2}$$$.

Kemudian $$$du=\left(\frac{x}{2}\right)^{\prime }dx = \frac{dx}{2}$$$ (langkah-langkah dapat dilihat di »), dan kita memperoleh $$$dx = 2 du$$$.

Dengan demikian,

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

Terapkan aturan pengali konstanta $$$\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$$$ dengan $$$c=2$$$ dan $$$f{\left(u \right)} = \sec^{2}{\left(u \right)}$$$:

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

Integral dari $$$\sec^{2}{\left(u \right)}$$$ adalah $$$\int{\sec^{2}{\left(u \right)} d u} = \tan{\left(u \right)}$$$:

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

Ingat bahwa $$$u=\frac{x}{2}$$$:

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

Oleh karena itu,

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

Tambahkan konstanta integrasi:

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

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