Exercise 2.2.4

Give an example of each or state that the request is impossible. For any that are impossible, give a compelling argument for why that is the case.

(a)
A sequence with an infinite number of ones that does not converge to one.
(b)
A sequence with an infinite number of ones that converges to a limit not equal to one.
(c)
A divergent sequence such that for every n ∈ N it is possible to find n consecutive ones somewhere in the sequence.

Answers

(a)
a n = ( − 1 ) n
(b)
Impossible, if lim ⁡ a n = a ≠ 1 then for any n ≥ N we can find a n with a n = 1 meaning 𝜖 < | 1 − a | is impossible.
(c)
a n = ( 1 , 2 , 1 , 1 , 3 , 1 , 1 , 1 , … )
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2022-01-27 00:00
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