I need help proving that the set: (1/2, 2/3, 3/4,...,n/n+1,...) is countable.
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Originally Posted by redwings6 I need help proving that the set: (1/2, 2/3, 3/4,...,n/n+1,...) is countable. Let . Now define by . Prove that is injective.
Originally Posted by redwings6 I need help proving that the set: (1/2, 2/3, 3/4,...,n/n+1,...) is countable. Alternatively, clearly is an overkill surjection. Clearly Plato's answer along with "every infinite subset of a countable set is countable" is better though.
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