Converge or diverge? (partial frac. long division)

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In summary, the conversation is about determining whether a given sequence converges or diverges and finding its limit. The speaker suggests using the integral test, but is unsure of how to proceed with it. Another speaker advises against using the integral test and suggests dividing the numerator and denominator by n^2 to find the limit. They clarify that taking the integral or derivative is not necessary and that the limit does not go to 0.
  • #1
SciSteve
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Determine whether the sequence converges or diverges. If it converges, find the limit.
An=7+4n^2/n+2n^2
I know you have to compare it to the integral of the same equation, so I do this and the only means of integration I believe to be is by partial fractions, since degree of top equals degree of bottom but I am stuck on the long division, haven't done it in so long can't remember how to. any tips would be great.
 
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  • #2
Forget the integral test for sequences. That's for summing series. To find the limit think about dividing the numerator and denominator by n^2. Does that ring a bell?
 
  • #3
the only thing is it says if it converges find the limit and i know it doesn't diverge so I need to find out the value do i still take the integral of it or what?
 
  • #4
all you ever do with sequences to find the value they approach is take the limit of it as n -> inf of your general term.

when you find the limit of a sequence all you do is take the limit of it. That's it.
 
  • #5
are you sure you don't take the integral or derivative? because if not there must be a trick to this one i find that the lim as n->inf. goes to 0 when plugging into the original given equation, but that isn't the right answer, any ideas?
 
  • #6
I am REALLY sure that i) there is no use in taking the integral and ii) you don't need to take the derivative. The limit as n->inf does not go to 0. I already told you what to do. Divide the numerator and denominator by n^2 and then take a another look at it.
 

What is "Converge or diverge?"

"Converge or diverge" refers to the behavior of a mathematical series or sequence. It is used to determine if the terms of the series or sequence approach a finite limit (converge) or if they grow without bound (diverge).

What is partial fraction long division?

Partial fraction long division is a method used to decompose a rational function into simpler fractions. It is typically used to solve integrals or to simplify complex expressions.

How do you determine if a series converges or diverges?

One way to determine the convergence or divergence of a series is to use the ratio test. This involves taking the limit of the absolute value of the ratio of consecutive terms in the series. If the limit is less than 1, the series converges. If the limit is greater than 1, the series diverges.

What are some common types of series that converge?

Geometric series, telescoping series, and p-series are some common types of series that converge. A geometric series has a constant ratio between consecutive terms, a telescoping series has terms that cancel each other out, and a p-series has the form 1/n^p where p is a positive constant.

How is partial fraction long division used to determine if a series converges or diverges?

Partial fraction long division can be used to break down a rational function into simpler fractions, which can then be evaluated for convergence or divergence. If the individual fractions converge, then the original series also converges. If any of the individual fractions diverge, then the original series also diverges.

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