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!

Combinatorial Identity

  1. Jun 22, 2005 #1
    Can someone help me how to deal with this identity that i must prove?

    [tex]{n + k-1 \choose n - 1} = \sum_{i=1}^k {k-1\choose i -1} {n \choose i}[/tex]

    I've tried to figure out what the combinatorial meaning of the right hand side is, but I didn't succeed :(
  2. jcsd
  3. Jun 22, 2005 #2
    I think it will help to rewrite it in the form:

    [tex]{n + k-1 \choose k} = \sum_{i=1}^k {k-1\choose k - i} {n \choose i}[/tex]
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Combinatorial Identity
  1. Component Identities (Replies: 3)

  2. Vector identity (Replies: 3)

  3. Trignometry Identities (Replies: 2)