Understanding telescoping series

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SUMMARY

The discussion centers on the evaluation of the telescoping series \(\sum _{n=1}^{\infty } \frac{1}{n(n+3)}\) using partial fraction decomposition. The series can be expressed as \(\sum _{n=1}^{\infty } \frac{1}{3n}-\frac{1}{3n+9}\), which reveals a cancellation pattern leading to the sum. Additionally, the discussion references a formula from Wikipedia stating that \(\sum^\infty_{n=1} {\frac{1}{n(n+k)}} = \frac{H_k}{k}\), where \(H_k\) is the \(k\)th harmonic number, indicating that all terms after \(1/(k - 1)\) cancel out.

PREREQUISITES
  • Understanding of telescoping series
  • Familiarity with partial fraction decomposition
  • Knowledge of harmonic numbers
  • Basic calculus concepts related to infinite series
NEXT STEPS
  • Study the properties of harmonic numbers and their applications
  • Explore advanced techniques in series convergence
  • Learn about other types of series, such as geometric and arithmetic series
  • Investigate the use of generating functions in series analysis
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Mathematicians, educators, and students interested in series convergence, particularly those focusing on telescoping series and their applications in calculus.

jinksys
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I understand that if given the following series:

[tex]\sum _{n=1}^{\infty } \frac{1}{n(n+3)}[/tex]

I can break it up using partial fraction decomposition into:

[tex]\sum _{n=1}^{\infty } \frac{1}{3n}-\frac{1}{3n+9}[/tex]

If I start listing the values of [tex]n_1,n_2[/tex], etc, I can see the cancellation pattern and find the sum.

This process seems tedious, is there another way of doing these problems?

Wikipedia says:

* Let k be a positive integer. Then

[tex]\sum^\infty_{n=1} {\frac{1}{n(n+k)}} = \frac{H_k}{k}[/tex]

where Hk is the kth harmonic number. All of the terms after 1/(k − 1) cancel.

But I'm not sure what the 1/(k - 1) means, nor do I understand the harmonic number bit either.
 
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I think that what you are doing is correct, and probably the intended method to use. Sometimes you just got to go ahead and brute force your way through it.
 
Pacopag said:
I think that what you are doing is correct, and probably the intended method to use. Sometimes you just got to go ahead and brute force your way through it.

Ok,

Do you know what my wikipedia snippet is referring to?
http://en.wikipedia.org/wiki/Telescoping_series
 

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