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: Problem with sigma notation

  1. May 3, 2007 #1
    must express this series using sigma notation


    i would be extremely grateful for some help

    I know that you use the infinite symbol and it goes above sigma and then n=1 below it.
    i also have used the arithmetic series equations and geometric equations on several other problems but i don't know where to start when the equation doesn't consist of one of these two and when the ratio isn't a constant additive, divisor, subtractor, or multiplicative
    Last edited: May 3, 2007
  2. jcsd
  3. May 3, 2007 #2
    Look at the numbers in the denominators. Do they remind you of something: 1,1,2,6,24,...? (No, it's not the Fibonacci series!) Pay attention to how one number is related to the subsequent one.
  4. May 4, 2007 #3
    As neutrino mentioned the denominator is interesting. Also just a note 0!=1 = 1!. This is the usuall definition.

    [This hint I think really gives the answer away]
  5. May 5, 2007 #4
    Do you know what a factoral is?
  6. May 6, 2007 #5
    Who are you refering too? I was reading this and made me wonder maby I was thinking wrong? I know whats a factorial and in my classes usually 0! is defined to be 1. Which was shown using the binomial theorum as I remember.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook