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!

Find a formula that generates a sequence

  1. Nov 19, 2012 #1
    1. The problem statement, all variables and given/known data

    Find a formula that generates the sequence:

    2/(3 x 4), -3/(4 x 5), 4/(5 x 6), -5/(6 x 7), . . .

    2. Relevant equations



    3. The attempt at a solution

    Here is what I have so far:

    a_n = -1(n/((n + 1)(n + 2)))

    Now, I'm stuck. The formula generates a negative number every time. I need a negative number every other time.
    Any suggestions?
     
    Last edited: Nov 19, 2012
  2. jcsd
  3. Nov 19, 2012 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Use something like (-1)^n?
     
  4. Nov 19, 2012 #3
    Yeah, that will work. Thanks!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Find a formula that generates a sequence
  1. Find sequence formula (Replies: 2)

Loading...