1. Not finding help here? Sign up for a free 30min 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!

Summation with combinations

  1. Oct 8, 2013 #1
    1. The problem statement, all variables and given/known data

    I'm trying to derive the PGF for the Binomial.


    3. The attempt at a solution

    I have it whittled down to [itex]\sum^{n}_{x=0}(nCx)(\frac{sp}{1-p})^x[/itex]

    I just don't know how to simplify this further. Any help is most appreciated.
     
  2. jcsd
  3. Oct 9, 2013 #2

    CompuChip

    User Avatar
    Science Advisor
    Homework Helper

    I think you lost some ##(1 - p)##s there, are you sure you didn't mean ##\sum_{x = 0}^n \binom{n}{x} (sp)^x (1 - p)^{n - x}##?

    The result should follow from the binomial theorem,
    $$ (x + y )^n = \sum_{k = 0}^n \binom{n}{k} x^{n-k} y^k. $$
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Summation with combinations
  1. Summation ? (Replies: 4)

  2. Question in summation (Replies: 9)

  3. Summation Question (Replies: 7)

  4. Summation problem (Replies: 4)

Loading...