I have a very simple problem. Assume we have a finite measure $\mu$ on $[1,\infty)$, and \begin{align} \int_1^\infty t ~d\mu(t) < \infty. \end{align} My question is if this implies \begin{align} \int_1^\infty t \ln t ~d\mu(t) < \infty. \end{align} It would be nice if this is true but maybe someone sees a simple counterexample?
2026-05-17 13:29:31.1779024571
If $\ln x$ is integrable, then is $x \ln x$ also integrable?
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Example: $d\mu(t) = {dt\over t^2\log^{3/2}(t+1)}$.