What is the sum of this infinite geometric series?

In summary, the conversation discusses a problem involving finding the sum of an infinite series, which is believed to be a geometric series but later determined to not be. The participants attempt to solve the problem and discuss different approaches, including the concept of telescoping sums and taking the limit of partial sums. The final solution is given as 60^(1/3) - 1.
  • #1
aces9113
17
0

Homework Statement



∑ ( 60^(1/(n+3)) − 60^(1/(n+4)) )
n = 0

Homework Equations


I believe this is a geometric series so the sum would equal a/(1-r)


The Attempt at a Solution


I tried to view it as a geometric series but i had trouble finding a ratio, especially what i thought was r (60) would make the series diverge
 
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  • #2
You are right that it's not geometric. You aren't going to have much luck actually finding a sum. Do you just want to show it converges?
 
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  • #3
Ever heard of the term telescopic sum? Try writing the sum up to n = 1, then n = 2, then for all n up to n = 3, and you will see what I mean.

(BTW: The answer is 60^(1/3) - 1.)
 
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  • #4
yes but I'm not entirely sure how to do them. when I do that, I am left with 60^(1/3) and then 60^(1/infinity+3) - 60^(1/infinity+4) which would end up being 60^(1/3) since the others cancel but this is wrong. what am i doing wrong?
 
  • #5
aces9113 said:
yes but I'm not entirely sure how to do them. when I do that, I am left with 60^(1/3) and then 60^(1/infinity+3) - 60^(1/infinity+4) which would end up being 60^(1/3) since the others cancel but this is wrong. what am i doing wrong?

Oh yeah, it does telescope in a manner of speaking. Thanks grey_earl. The terms in the split up series don't go to zero. You need to think of it as a limit of partial sums.
 
  • #6
Exactly. Calculate first [tex]\sum_{n=0}^N (60^{1/(n+3)} -60^{1/(n+4)})[/tex], and then take the limit [tex]N \rightarrow \infty[/tex].
 
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Related to What is the sum of this infinite geometric series?

1. What is an infinite series?

An infinite series is a mathematical concept that involves adding an infinite number of terms together. It is written in the form of ∑n=1 an, where n is the index of the terms and an is the value of each term.

2. How is the sum of an infinite series calculated?

The sum of an infinite series is calculated by finding the limit of the partial sums as the number of terms approaches infinity. This is known as the limit of the series or the series convergence.

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

A convergent series is one in which the sum of the terms approaches a finite value as the number of terms increases. A divergent series is one in which the sum of the terms either approaches infinity or does not have a finite limit.

4. What are some common types of infinite series?

Some common types of infinite series include geometric series, harmonic series, and alternating series. Each of these series has a specific pattern or rule for calculating the terms.

5. What is the importance of infinite series in science?

Infinite series are important in science because they allow us to approximate and calculate values of various phenomena, such as the behavior of systems with continuously changing variables. They are also used in many mathematical models and equations in various scientific fields.

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