Analysis of "Absolute Convergence" of $\sum_{n=2}^{\infty}\frac{1}{(lnn)^{n}}$

Click For Summary

Homework Help Overview

The discussion revolves around the analysis of the series $\sum_{n=2}^{\infty}\frac{1}{(lnn)^{n}}$, specifically focusing on the concept of absolute convergence and the application of convergence tests.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the idea of treating the series as a geometric series and discuss the implications of the ratio test. Questions arise regarding the definition of the variable r and its significance in determining convergence.

Discussion Status

The discussion is ongoing, with participants sharing their thoughts on the convergence tests and the behavior of the series. Some guidance has been offered regarding the ratio test and the conditions for convergence, but no consensus has been reached on the overall approach.

Contextual Notes

There are indications of confusion regarding the definition of r and its application in the context of the ratio test. Participants are also considering the implications of the series being ultimately decreasing.

rocomath
Messages
1,752
Reaction score
1
\sum_{n=2}^{\infty}\frac{1}{(lnn)^{n}}

If I treat it as a geometric series, then when n=3, r is smaller than 1

\sum_{n=2}^{\infty}(\frac{1}{ln3})^3

What matters is that it's ultimately decreasing, would that be the correct approach? Even problem, no answer!

Thanks.
 
Last edited:
Physics news on Phys.org
What is r?
 
Well, as for an answer I would like to say that:

When n=3, r equals

|\frac{1}{ln3}|<1

Which is true, and so, what matters is that it is ultimately decreasing.
 
In the ratio test r = Limn-->infinity|Ln(n+1)-(n+1)/Ln(n)-n|.

If r < 1 then the series converges.

But ultimately the ratio test is about whether you have a decreasing sequence; so I think you can use the ratio test here.

Also, for n > 1, absolute convergence is the same as convergence because Ln(n) > 0.
 
Last edited:

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K