Infinite Series with log natural Question

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SUMMARY

The discussion focuses on the convergence of the infinite series ∞Ʃ (-1)^(k+1) / kln(k) from k=2. The participant has attempted various tests including the ratio test, root test, and comparison test, with inconclusive results. The integral test is suggested as a more effective method for determining convergence. The participant is advised to consider the properties of ln(k) for k > 2 to facilitate the integral test.

PREREQUISITES
  • Understanding of infinite series and convergence tests
  • Familiarity with the integral test for convergence
  • Knowledge of logarithmic functions, specifically ln(k)
  • Basic skills in mathematical analysis and series manipulation
NEXT STEPS
  • Study the integral test for convergence in detail
  • Learn about the properties of logarithmic functions and their implications in series
  • Explore the comparison test and its applications in series convergence
  • Review the alternating series test for future reference
USEFUL FOR

Students studying calculus, particularly those focusing on series convergence, as well as educators seeking to enhance their understanding of convergence tests in mathematical analysis.

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Homework Statement



Ʃ (-1)^(k+1) / kln(k)
k=2

Homework Equations


integral test, p test, comparison test, limit comparison, ratio test, root test.


The Attempt at a Solution


In class so far we have not learned the alternating series test so i can't use that test.
So far I have done the test for divergent which turned up 0, ratio test which turned up 1, root test which didn't work, and its not a geometric or telescoping series.
I think that the only one that will work is the comparison test but I don't know what to use to compare this function.
 
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From your question I gather that you only need to say whether the series converges, not what the limit is.

Never mind my old post, it doesn't seem to help.

[old post]
I am not sure how much you have and haven't seen, but one common approach would be looking at the absolute value and using the triangle inequality to write

[tex]\left| \sum_{k = 2}^\infty \frac{(-1)^{k + 1}}{k \ln k} \right| \le \sum_{k = 2}^\infty \left| \frac{(-1)^{k + 1}}{k \ln k} \right|[/tex]

It may also be useful to note that ln k > 1 for k > 2.
[/old post]
[/color]

[new hint]
Whichever way you try the comparison test, it will always end up "going the wrong way".
Try an integral test instead.
 
Last edited:

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