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!

Homework Help: Rewritting sum as hyperbolic sine

  1. Oct 24, 2008 #1
    Hi all,

    I have to rewrite a serie into a fraction of hyperbolic sine but I am lost.... My problem looks like this

    [tex]\Sigma_{n=0}^{\infty} exp(K*F)*exp(-F*B(n+0.5))[/tex]

    which can be rearranged into

    [tex] exp(K*F)/(sinh(FB/2) [/tex]

    my problem is I cannot relate the serie


    any hints or advice appreciated.

    Thanks in advance

    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 24, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Take the 0.5 part out, so you have e^(FK)*e^(-FB/2)*e^(-FBn). You want the sum over n of e^(-FBn). That's the same as (e^(-FB))^n. It's a geometric series.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook