Let be a real number satisfying the property: For any nonnegative real numbers with their sum equal to , it is possible to arrange them around a circle such that the products of any two neighboring numbers are no greater than . Determine the minimum value of .
, 2013
Solution
Assume, without loss of generality, that
Because
to get the smallest possible maximum, the best arrangement around the circle is
In this case, the maximum is given by
We have
and the equality holds when , , and .
We have, on the other hand,
and the equality holds when , and .
Therefore, the minimum possible value of is .
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