Results 1 to 5 of 5

Math Help - Arithmetic Sequence

  1. #1
    Newbie
    Joined
    May 2010
    Posts
    20

    Arithmetic Sequence

    Hey guys, just a bit of help please.

    The first term of an arithmetic sequence is a. The mth term is zero. Find the rule for tn for the sequence.

    so far i got

    a=a+d(n-1)
    0=a+d(m-1)

    Subtract:

    a=d(n-1)-d(m-1)
    ...
    d=a/(n-m)

    so the rule i would write: t_n=a+a/(n-m)

    but this isn't right - can anyone see where i went wrong?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jan 2008
    Posts
    588
    Thanks
    87
    Quote Originally Posted by qwertyuiop View Post
    Hey guys, just a bit of help please.

    The first term of an arithmetic sequence is a. The mth term is zero. Find the rule for tn for the sequence.

    so far i got

    a=a+d(n-1)
    0=a+d(m-1)

    Subtract:

    a=d(n-1)-d(m-1)
    ...
    d=a/(n-m)

    so the rule i would write: t_n=a+a/(n-m)

    but this isn't right - can anyone see where i went wrong?
    I think there is some confusion in your notation because it's really the nth term a_n = a + (n-1)d. a simply equals a. At some point in your calculations, the two were mixed up and treated as a single variable. Your working seems fine, just redo the calculations, making careful distinctions between a_n and a.

    Another way to do this question is to simply add (md - md) = 0 to your equation for a_n
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    May 2010
    Posts
    20
    I see I see what i did wrong ! After like 2340928 times!
    haha
    Thank you so much Gusbob.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,085
    Thanks
    67
    Quote Originally Posted by qwertyuiop View Post
    I see I see what i did wrong ! After like 2340928 times!
    If 1 second for each time, then ~27 FULL days !
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    May 2010
    Posts
    20
    yea totally ! (:
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: August 24th 2010, 02:10 AM
  2. Arithmetic sequence
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: September 27th 2009, 03:37 PM
  3. Arithmetic sequence
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 17th 2009, 09:29 AM
  4. Arithmetic Sequence help!
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 15th 2009, 05:34 PM
  5. Replies: 12
    Last Post: November 15th 2006, 12:51 PM

Search Tags


/mathhelpforum @mathhelpforum