Sequence {(1/2)ln(1/n)} converge?

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In summary, the conversation discusses the convergence or divergence of the sequence {(1/2)ln(1/n)} and concludes that it diverges. The appropriate test is to show that the limit of the sequence as n approaches infinity is not equal to zero. This can be done analytically or through numerical calculations.
  • #1
garryh22
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Homework Statement



Does the sequence {(1/2)ln(1/n)} converge or diverge?

Homework Equations



Working it out analytically, I think it diverges. I would like to know the appropriate test to show this

The Attempt at a Solution

 
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  • #2
Seems to me that you can easily show that this diverges from the original definition. I presume that your numerical calculations (I'm not sure what you mean by "analytically". If you have show analytically that this diverges, you are done.) diverges to negative infinity.

That should lead you to look at (1/2)ln(1/n)< -M for M some large integer. Then ln(1/n)< -2M so 1/n< e-2M[/sum] and n> eM. Working the other way, for any integer M, if n< eM then (1/2)ln(1/n)< -M and so the sequence diverges.
 
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  • #3
Use the simplest test.

lim n -> inf gives (1/2)ln(0) which is not defined and clearly not zero. Therefore it diverges.
 

1. What is the sequence {(1/2)ln(1/n)}?

The sequence {(1/2)ln(1/n)} is a mathematical sequence that is defined by taking the natural logarithm of the inverse of n (1/n) and dividing it by 2. This sequence is commonly used in calculus and can be written as (1/2)ln(1/n) = ln[(1/n)^(1/2)].

2. Does the sequence {(1/2)ln(1/n)} converge or diverge?

It converges. As n approaches infinity, the value of (1/n)^(1/2) approaches 0, and the natural logarithm of 0 is -∞. Therefore, the limit of the sequence is -∞, indicating that it converges.

3. What is the limit of the sequence {(1/2)ln(1/n)}?

The limit of the sequence is -∞. As n approaches infinity, the value of (1/n)^(1/2) approaches 0, and the natural logarithm of 0 is -∞.

4. How do you prove that the sequence {(1/2)ln(1/n)} converges?

To prove that the sequence converges, you can use the definition of convergence, which states that a sequence converges to a limit L if for any positive number ε, there exists a positive integer N such that for all n>N, the absolute value of the difference between the sequence and the limit |a_n-L| is less than ε. In this case, as n approaches infinity, the sequence approaches -∞, and for any ε, there exists a positive integer N such that for all n>N, the absolute value of (1/2)ln(1/n) - (-∞) is less than ε, proving convergence.

5. What is the significance of the sequence {(1/2)ln(1/n)}?

The sequence has significance in calculus and mathematical analysis, as it is commonly used to demonstrate the concept of convergence and divergence in sequences. It also has applications in other areas of mathematics, such as in the study of infinite series and integrals.

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