TITLE: Evaluate a primitive of $1/(x\ln x)$
QUESTION [5 upvotes]: I have a problem when I want to  find
$$\int\frac{1}{x\ln x}\ dx.$$
I don't know how to start with, can anyone give me a hint? Thanks.

REPLY [6 votes]: $$
\int\frac{1}{x\ln x}\ dx=\int\frac{1}{\ln x}\ d(\ln x)=\ln|\ln x|+C\quad;\  x>0.
$$