Convergence comparison test (sequence, calc II)

Click For Summary

Homework Help Overview

The discussion revolves around the convergence of a sequence defined by the formula {An} = n!/(2^n). The original poster expresses difficulty with the factorial and the exponential component, indicating a concern about divergence and the need for guidance on convergence tests.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants suggest using the ratio test and question whether the problem pertains to a sequence or a series, indicating a need for clarification on the type of convergence being examined. There is also mention of the sandwich theorem as a potential approach.

Discussion Status

The discussion is active, with participants providing suggestions for methods to analyze the sequence's behavior. However, there is no explicit consensus on the best approach, and various interpretations of the problem are being explored.

Contextual Notes

The original poster notes that their instructor emphasizes checking for convergence before attempting to find limits, which may influence their approach to the problem.

coals
Messages
3
Reaction score
0

Homework Statement


Finally done with stupid improper integrals (calc 2 over summer is hard work, moving super fast) and now I'm sequences and series and what have you. I have another comparison test problem

Instructions are to find out if sequence converges or diverges, and find limit if it converges.

Sequence is:
{An}= n!/(2^n) .

The Attempt at a Solution


I know what to do with the factorial most of the time. I tried expanding it but the 2^n is throwing me off because the sequence diverges. Can i get a nudge in the right direction? I don't think my instructor wants me to find the limit of it if i can avoid doing so on divergence problems (he makes a point to tell us on HW to check convergence beforehand as practice for quizzes/tests).

As always thank all of you who help out pity-able college students as myself (lol) .
 
Physics news on Phys.org
You should really show us what you tried. But try a ratio test.
 
Its a sequence or a series ?
There is no comparison test for sequences.
If its a sequence: Try the sandwich theorem.
If its a series: See Dick's reply.
 
a_(n+1) / a_(n) >= 1, so the sequence monotonic increasing.
if you can't find a limit (number) then the series goes to infinity.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K