Find second order derivative of `tan^(-1)x`

Explanation

To find the second order derivative of \( f(x) = \tan^{-1}(x) \), we will follow these steps:

### Step 1: Find the first derivative \( f'(x) \)

The derivative of \( \tan^{-1}(x) \) is given by the formula:

\[
f'(x) = \frac{1}{1 + x^2}
...