Question

Find the second order derivatives of $\log x$

Answer 1

Let, $y=\log x$
$\Rightarrow \frac{dy}{dx}=\frac{d}{dx}\left(\log x\right)=\frac{1}{x}$
$\therefore$ $\frac{d^{2}y}{d{x}^2}=\frac{d}{dx}\left(\frac{1}{x}\right)=\frac{-1}{x^2}$