Solution
= Solution
The <product rule> gives
$$
\boxed{f'(x)=1-(\log x+1)=-\log x},\qquad f''(x)=-1/x.
$$
In particular, the second <derivative> is negative throughout the domain.
= Solution
The <product rule> gives
$$
\boxed{f'(x)=1-(\log x+1)=-\log x},\qquad f''(x)=-1/x.
$$
In particular, the second <derivative> is negative throughout the domain.