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## Main Question or Discussion Point

If A, B are nonempty subsets of R and A is a subset of B, how can you prove that: if A is unbounded, B is unbounded?

- Thread starter Seacow1988
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- #1

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If A, B are nonempty subsets of R and A is a subset of B, how can you prove that: if A is unbounded, B is unbounded?

- #2

gb7nash

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Suppose to the contrary that B is bounded. So there exists a real number M such that |b| < M for all b in B. Do you see where the problem lies?

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- #3

Landau

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If you understand the definition of 'boundedness' and 'subset' then this is trivial.

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