Does the series converge or diverge?

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Homework Help Overview

The problem involves determining the convergence of a monotone increasing sequence defined by the condition that the difference between consecutive terms is less than \(\frac{1}{n}\). Participants explore whether this condition guarantees convergence.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to use the triangle inequality to analyze convergence but finds it inconclusive. Another participant proposes a specific sequence to illustrate divergence, questioning the necessity of convergence under the given conditions.

Discussion Status

The discussion includes various interpretations of the sequence's behavior, with some participants supporting the idea that it may not converge. There is an exchange of ideas regarding the implications of the sequence's definition and the conditions for convergence.

Contextual Notes

Participants note the challenge of typing mathematical expressions on mobile devices, which may affect clarity in communication. The original poster expresses uncertainty about the convergence of the sequence despite initial instincts suggesting it converges.

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Homework Statement


Let [tex]x_{n}[/tex] be a monotone increasing sequence such that [tex]x_{n+1}-x_{n}< \frac{1}{n}.[/tex] Must [tex]x_{n}[/tex] converge ?

Homework Equations



Instinctively, I think it converges since the terms "bunch" up as n increases.

The Attempt at a Solution


[tex]|x_{n+1}-L| \leq |x_{n+1}-x_{n}| + |x_{n}-L|[/tex].
[tex]|x_{n+1}-L|< \frac{1}{n}+ |x_{n}-L|[/tex] . But this doesn't tell me anything about convergence.

If I apply the triangle inequality continuosly all I can see is that
[tex]|x_{n+1}-L|< \sum\frac{1}{n}[/tex]

What can you guys tell me ?
 
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Great that makes sense. I had a feeling it need not converge but I was unsure. Does this work too...
Define a sequence such that [tex]x_{n}-x_{n-1}= \frac{1}{n}[/tex] such that the sequence has positive terms them
[tex]|x_{n} -L| =|1 + 1/2 + ...+ 1/n|[/tex ] which does not converge.<br /> I suppose that also works correct? <br /> Excuse my latex, typing from a phone is difficult.[/tex]
 
Last edited:
Yes, that works.
 
Thanks a lot for the help.
 
So what have you decided, does it converges or diverges? :)
 

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