Question

Find the second order derivatives of the function
$log\,x$

Answer 1

The correct answer is $\frac{-1}{x^2}$
Let $y=log\,x$
Then,
$\frac{dy}{dx}=\frac{d}{dx}(logx)=\frac{1}{x}$
$∴\frac{d^2y}{dx^2}=\frac{d}{dx}(\frac{1}{x})=\frac{-1}{x^2}$