Difference between revisions of "1984 USAMO Problems/Problem 2"

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== Problem ==
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The geometric mean of any set of <math>m</math> non-negative numbers is the <math>m</math>-th root of their product.
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<math>\quad (\text{i})\quad</math> For which positive integers <math>n</math> is there a finite set <math>S_n</math> of <math>n</math> distinct positive integers such that the geometric mean of any subset of <math>S_n</math> is an integer?
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<math>\quad (\text{ii})\quad</math> Is there an infinite set <math>S</math> of distinct positive integers such that the geometric mean of any finite subset of <math>S</math> is an integer?
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==Solution==
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{{solution}}
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== See Also ==
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{{USAMO box|year=1984|num-b=1|num-a=3}}
 
{{MAA Notice}}
 
{{MAA Notice}}
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[[Category:Olympiad Number Theory Problems]]

Revision as of 11:29, 18 July 2016

Problem

The geometric mean of any set of $m$ non-negative numbers is the $m$-th root of their product.

$\quad (\text{i})\quad$ For which positive integers $n$ is there a finite set $S_n$ of $n$ distinct positive integers such that the geometric mean of any subset of $S_n$ is an integer?

$\quad (\text{ii})\quad$ Is there an infinite set $S$ of distinct positive integers such that the geometric mean of any finite subset of $S$ is an integer?

Solution

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See Also

1984 USAMO (ProblemsResources)
Preceded by
Problem 1
Followed by
Problem 3
1 2 3 4 5
All USAMO Problems and Solutions

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