1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The sum of a series

  1. Sep 23, 2012 #1
  2. jcsd
  3. Sep 23, 2012 #2

    jbunniii

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

  4. Sep 23, 2012 #3
    you better use \frac{a}{b} to make clear what fraction you want to make.
    make sure to use [itex][/itex ] (but without the latter space before the bracket) to place the expression you want between those two.
     
  5. Sep 24, 2012 #4

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    You do it by finding the sum
    [tex] S(x) = \sum_{n=1}^{\infty} \frac{x^n}{n}[/tex] and then substituting the correct value of x.

    RGV
     
  6. Sep 24, 2012 #5

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Yes, the wolframAlpha link confirms that it's the same problem.

    @Badmouton,

    The expression you are summing, with the proper set of parentheses: 2/(n*7n).

    This equivalent to (2*7-n)/n also equivalent to (2*(1/7)n)/n .

    All of these are more readable using LaTeX, which allows you to include the summation symbol, Ʃ , along with the summation limits.

    [itex]\displaystyle \sum_{n=1}^{\infty} \frac{2}{n7^{n}}[/itex]

    [itex]\displaystyle \sum_{n=1}^{\infty} \frac{2\left(7^{-n}\right)}{n}[/itex]

    [itex]\displaystyle \sum_{n=1}^{\infty} \frac{2\left(\frac{1}{7}\right)^{n}}{n}[/itex]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: The sum of a series
  1. Sum of series (Replies: 2)

  2. Sum series (Replies: 1)

  3. Sum of Series (Replies: 10)

  4. Sum of a series (Replies: 11)

  5. Sum of a series (Replies: 15)

Loading...