IMO Shortlist 1966 problem 2
Dodao/la:
arhiva2. travnja 2012. Given
positive real numbers
such that
, prove that
%V0
Given $n$ positive real numbers $a_1, a_2, \ldots , a_n$ such that $a_1a_2 \cdots a_n = 1$, prove that
$$(1 + a_1)(1 + a_2) \cdots (1 + a_n) \geq 2^n.$$
Izvor: Međunarodna matematička olimpijada, shortlist 1966