Is this sequence divergent or convergent?

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Homework Help Overview

The discussion revolves around determining whether the sequence defined by {4 + sin(1/2 * pi * n)} converges or diverges, and if it converges, identifying the limit. Participants express confusion regarding the oscillatory nature of the sine function and its implications for the limit of the sequence.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the behavior of the sine function and its oscillation between -1 and 1, questioning how this affects the limit of the sequence. Some suggest that the limit may not exist due to this oscillation, while others propose specific values for the limit based on the sine function's behavior at certain points.

Discussion Status

The discussion is active, with various interpretations being explored regarding the limit of the sequence. Some participants have offered insights into the nature of the sequence and its possible values, while others are questioning the fundamental definitions of limits and the properties required for convergence.

Contextual Notes

Participants note that the sequence oscillates between three specific values: 3, 4, and 5, leading to questions about the existence of a single limit. There is also mention of the need to understand the definition of a limit in the context of this sequence.

Sarah Kenney
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Homework Statement


I'm trying to find out whether or not this sequence diverges or converges. If it converges, then what's the limit.
{4+sin(1/2*pi*n)}

The Attempt at a Solution


This one is a bit confusing to me since sin oscillates between 1 and -1. So if you plug in (pi*infinity)/2, that would go back and forth. So does that mean that the limit does not exist?

Thanks in advance.
 
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Sarah Kenney said:

Homework Statement


I'm trying to find out whether or not this sequence diverges or converges. If it converges, then what's the limit.
{4+sin(1/2*pi*n)}

The Attempt at a Solution


This one is a bit confusing to me since sin oscillates between 1 and -1. So if you plug in (pi*infinity)/2, that would go back and forth. So does that mean that the limit does not exist?

Thanks in advance.

If the limit does exist, what could it be?
 
PeroK said:
If the limit does exist, what could it be?

Would the limit be 5 since sin(pi\2) is 1?
 
Sarah Kenney said:
Would the limit be 5 since sin(pi\2) is 1?

How many different values does the sequence have?
 
Oh, so because it oscillates between -1 and 1, then the limit is from 3 to 5?
 
Sarah Kenney said:
Oh, so because it oscillates between -1 and 1, then the limit is from 3 to 5?

You can only have one limit (at most)! The sequence takes only three values: 3, 4 and 5. Do you just have to work out what the limit is (if it exists), or do you have to prove it?
 
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Sarah Kenney said:

Homework Statement


I'm trying to find out whether or not this sequence diverges or converges. If it converges, then what's the limit.
{4+sin(1/2*pi*n)}

The Attempt at a Solution


This one is a bit confusing to me since sin oscillates between 1 and -1. So if you plug in (pi*infinity)/2, that would go back and forth. So does that mean that the limit does not exist?

Thanks in advance.

You need to review the basics: what is the definition of a limit? Does your sequence have the required properties?
 
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Ok, I think I've got it. It does not exist, since the sequence oscillates between 5, 4, and 3. Thanks!
 

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