How Do I Apply Stolz-Cesaro Theorem to Find the Limit of a Sequence?

In summary, the limit of the given array, which is a sum of cosines, is being solved using Stolz-Cesaro theorem. However, to apply the theorem, another sequence needs to be used. The correct terms in the array should have been cos(π/n) and cos(π/2n). The solution is still incomplete.
  • #1
LazuRazvan
1
0

Homework Statement


hello, i have to find the limit of the next array

(xn)=(cos (π/n+1) + cos (π/n+2) + ...+ cos ( π/2n))/n
when n goes to infinity.

Homework Equations


I was told to apply stolz cesaro and that is where i ended up :
the limit is :

limit of cos ( π/2n+1) + cos (π/2n+2) -cos (π/n+1)

The Attempt at a Solution


How i finish this ?
 
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  • #2
LazuRazvan said:

Homework Statement


hello, i have to find the limit of the next array

(xn)=(cos (π/n+1) + cos (π/n+2) + ...+ cos ( π/2n))/n
What you wrote in the first term was ##\cos(\frac{\pi}{n} + 1)##, and similar in the other two terms. Is that what you intended?
LazuRazvan said:
when n goes to infinity.

Homework Equations


I was told to apply stolz cesaro and that is where i ended up :
the limit is :

limit of cos ( π/2n+1) + cos (π/2n+2) -cos (π/n+1)
Same comment as above.

Also, to apply Stolz-Cesaro (https://en.wikipedia.org/wiki/Stolz–Cesàro_theorem), you need to use it with another sequence. What's the other sequence you are using?
LazuRazvan said:

The Attempt at a Solution


How i finish this ?
 
Last edited:

What is the Stolz-Cesàro array limit?

The Stolz-Cesàro array limit, also known as the Stolz-Cesàro theorem, is a mathematical theorem that states the limit of a sequence can be calculated by taking the ratio of the difference between consecutive terms and the difference between consecutive terms of a related sequence. This theorem is useful in determining the convergence of infinite series.

How is the Stolz-Cesàro array limit used?

The Stolz-Cesàro array limit is used to calculate the limit of a sequence that is difficult to evaluate directly. By taking the ratio of differences between terms, it can simplify the calculation and provide a more accurate result.

What is the difference between the Stolz-Cesàro array limit and the Cesàro mean?

The Stolz-Cesàro array limit is a specific application of the more general Cesàro mean. While the Stolz-Cesàro array limit uses the ratio of differences between consecutive terms, the Cesàro mean can use different operations, such as the arithmetic mean or geometric mean, to calculate the limit of a sequence.

What are some real-world applications of the Stolz-Cesàro array limit?

The Stolz-Cesàro array limit has applications in various fields, including physics, engineering, and finance. For example, it can be used to determine the convergence of infinite series in physics equations or to analyze the stability of a control system in engineering. It can also be used to calculate the average rate of return in financial investments.

Are there any limitations to the Stolz-Cesàro array limit?

While the Stolz-Cesàro array limit is a useful tool in determining the limit of a sequence, it cannot be applied to all sequences. It is only valid for sequences that satisfy certain conditions, such as a strictly increasing or decreasing sequence. It also cannot be used when the original sequence has a finite limit. In these cases, other methods may need to be used to calculate the limit.

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