Integral of $$$\sec^{2}{\left(x + 1 \right)}$$$

Find $$$\int \sec^{2}{\left(x + 1 \right)}\, dx$$$.

Let $$$u=x + 1$$$.

Then $$$du=\left(x + 1\right)^{\prime }dx = 1 dx$$$ (steps can be seen »), and we have that $$$dx = du$$$.

Thus,

$${\color{red}{\int{\sec^{2}{\left(x + 1 \right)} d x}}} = {\color{red}{\int{\sec^{2}{\left(u \right)} d u}}}$$

The integral of $$$\sec^{2}{\left(u \right)}$$$ is $$$\int{\sec^{2}{\left(u \right)} d u} = \tan{\left(u \right)}$$$:

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

Recall that $$$u=x + 1$$$:

$$\tan{\left({\color{red}{u}} \right)} = \tan{\left({\color{red}{\left(x + 1\right)}} \right)}$$

Therefore,

$$\int{\sec^{2}{\left(x + 1 \right)} d x} = \tan{\left(x + 1 \right)}$$

Add the constant of integration:

$$\int{\sec^{2}{\left(x + 1 \right)} d x} = \tan{\left(x + 1 \right)}+C$$

$$$\int \sec^{2}{\left(x + 1 \right)}\, dx = \tan{\left(x + 1 \right)} + C$$$A