Does this series converge or diverge?

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Homework Help Overview

The discussion revolves around the convergence or divergence of the series defined by the expression n = 1 to infinity of (n * sin(1/n)). Participants are exploring the nature of this series, particularly focusing on the behavior of the terms as n approaches infinity.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants are attempting to classify the series, with some suggesting it resembles a geometric series. There are discussions about the limit of sin(1/n) and its implications for the series' terms. Questions arise regarding the notation used and the validity of certain assumptions about the terms approaching zero.

Discussion Status

The discussion is active, with participants providing hints and questioning each other's reasoning. Some guidance has been offered regarding the comparison test and the importance of the limit of the terms in determining convergence. Multiple interpretations of the series' behavior are being explored.

Contextual Notes

There is some confusion regarding notation, specifically whether 'E' refers to a sigma notation. Additionally, participants are grappling with the implications of limits and the conditions for convergence, particularly the necessity for terms to approach zero.

rcmango
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Homework Statement



n = 1 E infinity (n * sin (1/n))

Homework Equations



geometric series test?

The Attempt at a Solution



It looks like a geometric series.

i know that sin 1/n = 0 by squeeze theorem.

n * 0 will always be 0.

am i on the right track, please help.
 
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rcmango, you really have to work on your notation. Is the 'E' supposed to be a sigma? If so then the nth term of your series tends to one. Can it converge?
 
Hint: try applying your logic to n/n.
 
rcmango said:

Homework Statement



n = 1 E infinity (n * sin (1/n))

Homework Equations



geometric series test?

The Attempt at a Solution



It looks like a geometric series.

i know that sin 1/n = 0 by squeeze theorem.
No, you don't know that! You only know that the limit is 0.

n * 0 will always be 0.
But none of your terms is n* 0 so that is irrelevant.

am i on the right track, please help.
No!
 
Okay, thanks Dick, you limit is 1.

i could use the comparison test, compare to 1/n
divide an / bn and get 1 by the nth term series. Thus diverging because it doesn't = 0.

thats what i made out of it. thanks a lot.
 
rcmango said:
Okay, thanks Dick, you limit is 1.

i could use the comparison test, compare to 1/n
divide an / bn and get 1 by the nth term series. Thus diverging because it doesn't = 0.

thats what i made out of it. thanks a lot.

Pretty good. Except a ratio test giving you a limit of one doesn't tell you much. You could do a comparison with 1/n, that works. But it's still overkill. If the nth term of a series doesn't approach zero then it doesn't converge. Period. Ever.
 

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