IMO Shortlist 1984 problem 20
Dodao/la:
arhiva2. travnja 2012. Determine all pairs

of positive real numbers with

such that
%V0
Determine all pairs $(a, b)$ of positive real numbers with $a \neq 1$ such that
$$\log_a b < \log_{a+1} (b + 1).$$
Izvor: Međunarodna matematička olimpijada, shortlist 1984