Question

Second order derivative of (log x-x) is

Answer 1

as

log_xx = 1

So

$\cfrac{d^2}{dx^2} ( log_x x)= \cfrac{d}{dx}[\cfrac{d}{dx} (log_x x)]$

Also,

$\cfrac{d}{dx}[\cfrac{d}{dx} (log_x x)]= \cfrac{d}{dx}[\cfrac{d}{dx} ( 1)] = 0$

And hence the answer is 0