Give an example of such a convergent series

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Homework Help Overview

The discussion revolves around finding an example of a convergent series \(\Sigma z_{n}\) where the limit superior of the absolute ratio of consecutive terms exceeds 1. Participants are exploring the properties of series convergence and the implications of the ratio test.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • One participant suggests combining the series \(2^{-n}\) and \(3^{-n}\) by alternating terms, while another participant questions whether this approach results in a limit superior of 1, indicating a need for further examination of the assumptions involved.

Discussion Status

The discussion is active, with participants sharing ideas and questioning the validity of their approaches. There is an acknowledgment of the potential issue with the limit superior in the proposed method, suggesting a productive exploration of the topic.

Contextual Notes

Participants are working under the constraint of providing an example that meets specific criteria regarding the limit superior of the series terms, which may influence their reasoning and suggestions.

gas8
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Homework Statement



Give an example of a convergent series [tex]\Sigma[/tex] z[tex]_{n}[/tex]

So that for each n in N we have:

limsup [tex]abs{\frac{z_{n+1}}{z_{n}}}[/tex] is greater than 1
 
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How about combining the convergent series 2^(-n) and 3^(-n) in a clever way? Hint: alternate terms from each.
 


yeah thx, I used 2^(-n) when n is even and 2^-(n+1 ) when n is odd
 


gas8 said:
yeah thx, I used 2^(-n) when n is even and 2^-(n+1 ) when n is odd

Something like that will work, but doesn't that just give you limsup=1?
 

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