Absolute convergence proving that limit =1

Click For Summary

Homework Help Overview

The discussion revolves around evaluating the limit as k approaches infinity of the absolute value of the expression (cos(πk + π))/(cos(πk)). The subject area pertains to limits and trigonometric functions.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to understand why the limit equals 1, with some questioning the behavior of the cosine function at integer multiples of π. There is also a suggestion to consider the alternating nature of the cosine function.

Discussion Status

Participants are engaged in exploring the limit and its properties, with some expressing confusion and seeking clarification. There is a recognition of the alternating values of the cosine function, but no consensus has been reached on the limit itself.

Contextual Notes

Some participants mention having consulted various sources without finding satisfactory explanations, indicating a potential gap in understanding or available resources.

Chaoticoli
Messages
8
Reaction score
0

Homework Statement


limit as k--> infinity ABS VALUE((cos(pi*k+pi))/(cos(k*pi)))


Homework Equations





The Attempt at a Solution



Can someone prove to me why this limit is equal to 1? I have tried several other sources and I have not had any luck.
 
Physics news on Phys.org
Chaoticoli said:

Homework Statement


limit as k--> infinity ABS VALUE((cos(pi*k+pi))/(cos(k*pi)))

Homework Equations



The Attempt at a Solution



Can someone prove to me why this limit is equal to 1? I have tried several other sources and I have not had any luck.
If k is an integer, what is cos(πk) ?
 
It must alternate between -1 and 1.
 
Chaoticoli said:

Homework Statement


limit as k--> infinity ABS VALUE((cos(pi*k+pi))/(cos(k*pi)))

I have tried several other sources and I have not had any luck.

Tried other sources? Have you tried working it yourself? What have you done so far?
 
Chaoticoli said:
It must alternate between -1 and 1.

What is \displaystyle\ \left|\frac{\pm1}{\pm1}\right|\ ?
 
I understand now. Thanks :)
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K