That is, let (an)∞n=1 and (bn)∞n=1 be sequences such that bnn→∞→0 and for all k∈N and l≥k,
|al−ak|<bk.
Show that (an)∞n=1 is Cauchy.
My guess is that an→0. So, we could try working from the definition of convergence and show that an→0, but it isn't clear to me how to show that |an|<ϵ.
Hints, not complete solutions, are appreciated.
Edit: Could the squeeze theorem potentially be useful here?
Answer
Hint: Let ϵ>0. Then there exists N such that bn<ϵ for n≥N. What happens if k,l≥N?
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