Convergence or Divergence of a Series with Sinusoidal General Term

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Homework Help Overview

The discussion revolves around the convergence or divergence of a series defined by the general term \( a_n = \sum_{n=1}^{\infty} n \sin\left(\frac{1}{n}\right) \). Participants are exploring various methods to analyze the series' behavior.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts the comparison test and the integral test but encounters difficulties. Some participants suggest trying the Nth Term Test and question whether the general term approaches zero as \( n \) increases.

Discussion Status

Participants are actively discussing different tests for convergence and divergence. There is a mix of suggestions and attempts to clarify the problem, but no consensus has been reached regarding the series' behavior.

Contextual Notes

There are indications of confusion regarding the problem setup, with one participant suggesting a review of the question. Additionally, there is a reference to Cauchy's Fundamental test for Divergence, though it is not universally accepted in the discussion.

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Homework Statement



an = sum of n * sin([tex]\frac{1}{n}[/tex] )from n =1 to n =infinity

Homework Equations



Test the series for convergence or divergence

The Attempt at a Solution


I tried the comparison test with bn = sum of n but it fails because an < bn
which means a series smaller than a divergent series and this gives me no information about the an ... I tried also the integral test but I couldn't do the integration ... so what do u think guys ?
 
Last edited:
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Try the Nth Term Test. :smile:

Hint: Without doing the test, you can see that you'd be adding 1 forever...
 
Last edited:
check the problem again
 
It's not nice to change the question when the expert isn't looking...

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Hence by Cauchy's Fundamental test for Divergence, as the limit is not zero, the series diverges. (http://www.math.oregonstate.edu/hom...StudyGuides/SandS/SeriesTests/divergence.html)
 
Since this isn't an alternating series, does the general term go to zero as n goes to infinity?

Edit: Didn't see SVXX's post before I replied. :wink:
 

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