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!

Solve The Series

  1. Jun 4, 2013 #1
    [tex] S_n = \sum_{k=1}^ {4n} {(-1)^\frac{k(k+1)}{2}} {k^2} [/tex].

    Then Sn can take what values among:
    1056, 1088, 1120, 1332
  2. jcsd
  3. Jun 4, 2013 #2


    User Avatar
    Science Advisor
    Homework Helper

    hi klen! :wink:

    simplest way is probably to do the sum for 4m-3,4m-2,4m-1,4m (only) first …

    what do you get? :smile:
  4. Jun 4, 2013 #3


    User Avatar
    Staff Emeritus
    Science Advisor

    Did you, for example, notice that every time n increases by 1, the sum has 4 new terms, two negative and two positive? Do you notice that for n= 1, so there are 4 terms, the sum is 20= 4(5) and when n= 2, so there are 8 terms, the sum is 72= 8(9)?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Solve The Series
  1. Solve For It (Replies: 2)

  2. Solve It! (Replies: 2)

  3. A series (Replies: 2)

  4. Sum of Series (Replies: 39)