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!

Messing around with summation operators

  1. Dec 2, 2009 #1
    1. The problem statement, all variables and given/known data

    I'm just not sure how to change the operators in summation, can anyone help?

    Let [tex]s_{n}=\sum_{k=1} ^n ((-1)^{k+1})/k[/tex]

    what is [tex]s_{2n}[/tex]?


    2. Relevant equations

    [tex]s_{n}=\sum_{k=1} ^n ((-1)^{k+1})/k[/tex]

    3. The attempt at a solution

    [tex]s_{2n}=\sum_{k=1} ^{2n} ((-1)^{2k+1})/2k[/tex]

    or

    [tex]s_{2n}=\sum_{k=1} ^{2n} ((-1)^{2k+2})/2k[/tex]

    This is in order to figure out a series proof, I just think I am really naive.
     
  2. jcsd
  3. Dec 2, 2009 #2

    Mark44

    Staff: Mentor

    No
    No
    How would you write s5 as a summation (not expanded)? How about s10? Don't overthink this problem.
     
  4. Dec 4, 2009 #3
    Thanks! I guess I tried to overthink, I've just seen people do amazing things with summation sings and sequences, I just tried to imitate.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Messing around with summation operators
  1. Exponets messing me up (Replies: 5)

  2. Summation of series (Replies: 4)

  3. Summation question (Replies: 5)

  4. Summation by steps (Replies: 7)

Loading...