Testing convergence of sequence

In summary, the first series converges due to being dominated by the convergent 1/n^2 series, while the second series' convergence is uncertain, as it is only a clue. The p-series test was used for the first series and the root test for the second series, but there is a possibility of using the wrong rules.
  • #1
jlu
3
0
how can i can the convergence of sum[sin (0.4)n / n pi]2 and that sum[sin (0.4)n / n pi] diverges, n is between -infinity and + infinity
 
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  • #2
jlu said:
how can i can the convergence of sum[sin (0.4)n / n pi]2 and that sum[sin (0.4)n / n pi] diverges, n is between -infinity and + infinity

The first series converges because it is dominated by 1/n^2 series, which is convergent. The second is harder - the 1/|n| series diverges, but this is only a clue.
 
  • #3
i used p-series test for the first one and root test for the second one. i stand to be corrected if i used the wrong rules
 

1. What is the definition of convergence in a sequence?

Convergence in a sequence refers to the behavior of the terms in a sequence approaching a certain value as the number of terms increases. In other words, the terms in the sequence get closer and closer to a fixed value as more terms are added.

2. How do you test for convergence in a sequence?

There are a few different tests that can be used to determine convergence in a sequence, such as the limit test, ratio test, and root test. These tests involve evaluating the limit of the sequence or comparing it to a known convergent or divergent sequence.

3. What is the difference between absolute and conditional convergence?

Absolute convergence refers to a sequence where the terms always approach a certain value, regardless of the order in which they are added. On the other hand, conditional convergence refers to a sequence where the terms only approach a certain value when they are added in a specific order.

4. Can a sequence converge to more than one value?

No, a sequence can only converge to one value. If a sequence approaches more than one value, it is considered to be divergent.

5. What happens when a sequence does not converge?

If a sequence does not converge, it is considered to be divergent. This means that the terms in the sequence do not approach a fixed value, and the behavior of the terms may be unpredictable.

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