2001 USAMO Problems/Problem 5
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Problem
Let
be a set of integers (not necessarily positive) such that
(b) if
and
are elements of
(possibly equal), then
also belongs to
.
Prove that
is the set of all integers.
Solution
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See also
| 2001 USAMO (Problems • Resources: AoPS | ML) | ||
| Preceded by Problem 4 | 1 • 2 • 3 • 4 • 5 • 6 | Followed by Problem 6 |






