What is $\frac{d}{dx}\left(\log{\left(x^{2} + 1 \right)}\right)$?

Explanation

1. 01

   $\frac{d}{dx}\log u = \frac{u'}{u}$ with $u = x^{2} + 1$.

2. 02

   $\frac{2x}{x^{2} + 1}$.