Is This Infinite Series Convergent?

In summary, an infinite series is a mathematical concept that represents the sum of an infinite number of terms. To determine if an infinite series converges or diverges, various tests such as the ratio test, comparison test, and integral test can be used. Not all infinite series can be solved, but many can using mathematical techniques. There are real-life applications of infinite series in fields such as physics, engineering, and finance. Common techniques used to solve infinite series include the geometric series formula, telescoping series, and the method of partial sums.
  • #1
Imaxx
5
0
Homework Statement
solve this infinite series
Relevant Equations
.

∑ (n∧2+3n+1) / (n∧4+2n∧3+n∧2) =?
n=1

I attempted to find the general sum of this 'expression'?? But no luck. How can I solve this?
 
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  • #2
Do you know what ##\sum n ## and ##\sum n^2## are?
 
  • #3
from what to what? 1 to ∞?
 
  • #4
Imaxx said:
from what to what? 1 to ∞?
Sorry, I missed the denominator. You should really have used LaTeX. One formula isn't a big deal.

Can you cancel your quotient and factorize the denominator?
 
  • #5
If you have no typo, then you will probably have to consider the sequence of partial sums.
 
  • #6
You might try separating the original series into three series, one for each term in the numerator, and seeing if you can evaluate those.

Just do a partial fraction expansion. It's a telescoping series.
 
Last edited:
  • #8
I feel a bit ashamed that there's a mistake in the code block after getting two likes. :sorry:
Here's the correct version
Code:
$$\sum_{n=1}^{\infty} \frac{n^2+3n+1}{n^2(n+1)^2}$$
Sorry for bumping up the post.
 
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  • #9
archaic said:
I feel a bit ashamed that there's a mistake in the code block after getting two likes. :sorry:
Here's the correct version
Code:
$$\sum_{n=1}^{\infty} \frac{n^2+3n+1}{n^2(n+1)^2}$$
Sorry for bumping up the post.

Now I feel ashamed for not noticing either 😟
 
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  • #11
The OP cheated and managed to inveigle his way to a full solution:
https://www.physicsforums.com/threads/how-to-prove-this-infinite-series.992669/

I like to take the chance and remind you of our rules:
  • please report homework questions in technical forums, instead of answering them
  • do not provide full answers, that doesn't help the OP to understand their problem, even in technical forums
  • do not open multiple threads on the same topic
  • homework questions (anyway where they have been posted) require some efforts to be shown from the OP. We are not a solution automaton. Our goal is to teach, not to solve.
This thread is closed.
 
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FAQ: Is This Infinite Series Convergent?

How do I determine the convergence of an infinite series?

The convergence of an infinite series can be determined by using various tests such as the ratio test, comparison test, or the integral test. These tests help to determine if the series will approach a finite value or if it will diverge to infinity.

What is the difference between a convergent and a divergent series?

A convergent series is one in which the sum of all the terms approaches a finite value as the number of terms approaches infinity. On the other hand, a divergent series is one in which the sum of all the terms approaches infinity as the number of terms approaches infinity.

How can I find the sum of an infinite series?

The sum of an infinite series can be found by using various methods such as the geometric series formula, telescoping series, or by using mathematical software. However, not all infinite series have a finite sum, so it is important to determine the convergence of the series first.

Can I use the same method to solve all infinite series?

No, different methods may be required to solve different types of infinite series. For example, the geometric series formula can only be used for geometric series, while the integral test can only be used for certain types of series. It is important to understand the properties of the series before choosing a method to solve it.

Are there any shortcuts to solving infinite series?

There are some shortcuts that can be used for specific types of series, such as the geometric series formula or the telescoping series method. However, for most infinite series, there is no shortcut and it is important to use the appropriate test or method to determine the convergence and sum of the series.

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