sum of 1 + 3(x^2) + 5(x^3) + 7(x^5) +...+39(x^5)

Discussion in 'CT1' started by eddiecibrian, Apr 6, 2011.

  1. eddiecibrian

    eddiecibrian Member

    Is there any way to write 1 + 3(x^2) + 5(x^3) + 7(x^4) +...+39(x^20) into a geometric formula?

    Thanks for any help in advance:)
     
    Last edited by a moderator: Apr 6, 2011
    eddiecibrian, Apr 6, 2011
    #1
  2. bystander

    bystander Member

    Your end term looks odd.

    Its a sort of increasing annuity so try breaking it down:

    1 + x^2 + x^3 etc is a standard progression

    PLUS
    2x^2 + 4x^3 + 6x^4 etc
    which is 2* increasing annuity.

    Is that any help>?
     
    bystander, Apr 7, 2011
    #2
  3. DevonMatthews

    DevonMatthews Member

    I assume your talking about annuitites..

    Bystander is correct, In this case your after 1 + 3v^2 + 5v^3 + ... + 39v^20

    You can match this by doing 2(Ia)_20 - a_20 - v + 1 for instance, there are a number of ways to do this.
     
    Last edited by a moderator: Apr 8, 2011
    DevonMatthews, Apr 8, 2011
    #3
  4. eddiecibrian

    eddiecibrian Member

    yp splitting it up into different annuities seems like the easiest option:) Thanks for clearing this up!
     
    eddiecibrian, Apr 9, 2011
    #4

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