Determining Convergence/Divergence Of Infinite Series

In summary, the conversation discusses finding a general term for an infinite series in order to evaluate it analytically. The solution to the problem is attached and it is mentioned that the series diverges by looking at a few terms. The use of the nth term test is suggested as a simple way to prove divergence, and it is confirmed that this test applies to the series in question.
  • #1
Bashyboy
1,421
5

Homework Statement


I attached the solution to the problem.


Homework Equations





The Attempt at a Solution


I can see that the infinite series diverges by looking at a few terms, but how would I find a general term for the infinite series, to evaluate it analytically?
 

Attachments

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  • #2
Bashyboy said:
I can see that the infinite series diverges by looking at a few terms, but how would I find a general term for the infinite series, to evaluate it analytically?

If your goal is to prove that the series diverges, you don't necessarily need to find an expression for the general term (by which I assume you mean the n'th partial sum).

There is a very simple test which you should always apply as the first step. If this test fails, the series diverges. What test am I referring to?
 
  • #3
Would it be the nth term test?
 
  • #4
Yes. What does that test imply for this series?
 

FAQ: Determining Convergence/Divergence Of Infinite Series

1. What is the definition of convergence and divergence of an infinite series?

The convergence of an infinite series refers to the property that the sum of the terms in the series approaches a finite number as the number of terms increases indefinitely. Conversely, divergence occurs when the sum of the terms becomes infinitely large as the number of terms increases.

2. How do you determine the convergence or divergence of an infinite series?

To determine the convergence or divergence of an infinite series, you must evaluate the limit of the sequence of partial sums. If this limit exists and is a finite number, then the series is said to converge. If the limit does not exist or is infinite, then the series is said to diverge.

3. What is the significance of the ratio and root tests in determining convergence or divergence?

The ratio and root tests are two commonly used tests in determining the convergence or divergence of an infinite series. These tests provide a way to analyze the behavior of the terms in the series and determine if the series converges or diverges based on the values of the terms.

4. Can an infinite series converge to a negative number?

No, an infinite series cannot converge to a negative number. The convergence of a series means that the sum of the terms approaches a finite number, and a negative number is not considered a finite number.

5. What is the importance of determining the convergence or divergence of an infinite series?

Determining the convergence or divergence of an infinite series is important in various fields of mathematics, such as calculus and differential equations. It allows us to understand the behavior and properties of infinite sums and to make accurate calculations and predictions in real-world applications.

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