Results 1 to 6 of 6
Like Tree2Thanks
  • 1 Post By MarkFL
  • 1 Post By MarkFL

Math Help - Arithmetic Sequence

  1. #1
    Newbie
    Joined
    Nov 2012
    From
    Vancouver
    Posts
    21

    Arithmetic Sequence

    In an arithmetic sequence, the 11th term is 53 and the sum ofof the 5th and 7th terms is 56. Find the first 3 terms of the sequence.


    I'm trying to use the formula: tn= t1+(n-1)d but cant figure out where to get the numbers. Please step by step on how to get answer would be really helpful. Thanks
    Last edited by Vince604; November 15th 2012 at 10:50 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor MarkFL's Avatar
    Joined
    Dec 2011
    From
    St. Augustine, FL.
    Posts
    1,988
    Thanks
    734

    Re: Arithmetic Sequence

    Using the given information, we obtain two equations in two unknowns:

    t_1+10d=53

    (t_1+4d)+(t_1+6d)=56\,\therefore\,2t_1+10d=56

    If we subtract the first equation from the second, we will eliminate d and we can solve for t_1. Then we can use this value to find d from either of the original equations.
    Thanks from Vince604
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Nov 2012
    From
    Vancouver
    Posts
    21

    Re: Arithmetic Sequence

    is t1 = 3?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor MarkFL's Avatar
    Joined
    Dec 2011
    From
    St. Augustine, FL.
    Posts
    1,988
    Thanks
    734

    Re: Arithmetic Sequence

    Yes, so what is d?
    Thanks from Vince604
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Nov 2012
    From
    Vancouver
    Posts
    21

    Re: Arithmetic Sequence

    oh sweet thanks so much! d=5 i got it now. everything fell into place
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor MarkFL's Avatar
    Joined
    Dec 2011
    From
    St. Augustine, FL.
    Posts
    1,988
    Thanks
    734

    Re: Arithmetic Sequence

    Yes, good work!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: August 24th 2010, 03:10 AM
  2. Arithmetic Sequence
    Posted in the Algebra Forum
    Replies: 4
    Last Post: February 5th 2010, 12:08 AM
  3. arithmetic sequence
    Posted in the Calculus Forum
    Replies: 1
    Last Post: August 13th 2009, 12:37 PM
  4. Arithmetic sequence
    Posted in the Algebra Forum
    Replies: 6
    Last Post: May 8th 2007, 06:14 PM
  5. Replies: 12
    Last Post: November 15th 2006, 01:51 PM

Search Tags


/mathhelpforum @mathhelpforum