Results 1 to 11 of 11

Math Help - Converting partial sum to infinite series

  1. #1
    Member
    Joined
    Oct 2010
    Posts
    95

    Converting partial sum to infinite series

    If a partial sum of a series is given this way:

    Then, can I say since the ,



    Is this right? Can I do this to find the series of the partial sum equation of ?

    Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    Quote Originally Posted by xEnOn View Post
    If a partial sum of a series is given this way:

    Then, can I say since the ,



    Is this right? Can I do this to find the series of the partial sum equation of ?

    Thanks!
    No; the series isn't geometric.

    Find the traditional way. ()
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Oct 2010
    Posts
    95
    But if say I want to find Xn of this:


    Is there a way to solve for in the summation?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    Quote Originally Posted by xEnOn View Post
    But if say I want to find Xn of this:


    Is there a way to solve for in the summation?
    Use my formula in post #2 to find the nth term.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Oct 2010
    Posts
    95
    hmm...I am not very sure how I can use the formula. I haven't tried this before. Is the ?

    And then I have something like this: ?
    But this looks weird because Tn will become 0.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    Quote Originally Posted by xEnOn View Post
    hmm...I am not very sure how I can use the formula. I haven't tried this before. Is the ?

    And then I have something like this: ?
    But this looks weird because Tn will become 0.
    The nth term

    =

    =

    =

    =
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Member
    Joined
    Oct 2010
    Posts
    95
    But the difference between the sum of (0 to n) and sum of (0 to n-1) is not always the same. So this isn't the kind of usual arithmetic series and I cannot just say this is it right?

    And since it is going to be an infinite series, don't I have to take some kind of limits towards infinity?
    Follow Math Help Forum on Facebook and Google+

  8. #8
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    Quote Originally Posted by xEnOn View Post
    But the difference between the sum of (0 to n) and sum of (0 to n-1) is not always the same. So this isn't the kind of usual arithmetic series and I cannot just say this is it right?

    And since it is going to be an infinite series, don't I have to take some kind of limits towards infinity?
    This series is neither arithmetic nor geometric.

    Follow Math Help Forum on Facebook and Google+

  9. #9
    Member
    Joined
    Oct 2010
    Posts
    95
    ohh.. So it could just be like a summation of the difference between the previous and current term to get the eventual sum of the equation. But would this be very accurate compared to the actual equation?

    Thank you so much!!
    Follow Math Help Forum on Facebook and Google+

  10. #10
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    Quote Originally Posted by xEnOn View Post
    ohh.. So it could just be like a summation of the difference between the previous and current term to get the eventual sum of the equation. But would this be very accurate compared to the actual equation?

    Thank you so much!!
    More than accurate...it is exact!
    Follow Math Help Forum on Facebook and Google+

  11. #11
    Member
    Joined
    Oct 2010
    Posts
    95
    great! thanks for all the help!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Converting a series to AP
    Posted in the Number Theory Forum
    Replies: 4
    Last Post: January 13th 2011, 12:58 AM
  2. [SOLVED] Fourier series to calculate an infinite series
    Posted in the Differential Geometry Forum
    Replies: 1
    Last Post: August 4th 2010, 01:49 PM
  3. Replies: 7
    Last Post: October 12th 2009, 10:10 AM
  4. Replies: 2
    Last Post: September 16th 2009, 07:56 AM
  5. Replies: 1
    Last Post: May 5th 2008, 09:44 PM

Search Tags


/mathhelpforum @mathhelpforum