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!

Is my summation notation correct?

  1. Jan 14, 2013 #1
    It has been a while since I've had to figure out summation notation.
    Would you please look through my solutions, and tell me if they're correct?
    Thank you so much! :)
    1a.

    6
    Ʃ 1/6 = ?
    i=1

    1/6 + 1/6 + 1/6 + 1/6 + 1/6 +1/6 = 6/6 = 1

    What makes me doubt my answer is that it seems like the i=1 was for nothing...

    If the summation was for i/6, though, would this be correct?

    (1/6) + (2/6) + (3/6) + (4/6) + (5/6) + (6/6) = 21/6 = 7/2

    And if the summation were written like this:

    6
    Ʃ i/6 = ?
    i=3

    Would this be correct? (3/6) + (4/6) + (5/6) + (6/6) = 18/6 = 3

    1b.

    10
    Ʃ 1/10 = ?
    i=1

    (1/10)*10 = 10/10 = 1

    1c.

    100
    Ʃ 1/100 = (1/100)*100 = 100/100 = 1
    i=1
     
  2. jcsd
  3. Jan 14, 2013 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Looks fine to me.
     
  4. Jan 14, 2013 #3
    Oh, okay. Thank you! :)
     
  5. Jan 14, 2013 #4

    Mark44

    Staff: Mentor

    No, it serves a purpose. The index i doesn't explicitly appear in each term, but i = 1 gives the starting value of the index, and 6 gives the ending value. That says that there are 6 terms in the summation (6 - 1 + 1).

    In this summation ## \sum_{n = 3}^{25} n^2##, there are 25 - 3 + 1 = 23 terms.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Is my summation notation correct?
Loading...