Results 1 to 6 of 6

Math Help - I dont even know what to title this... help please :(

  1. #1
    Junior Member
    Joined
    Nov 2008
    Posts
    25

    I dont even know what to title this... help please :(

    Evaluate
    100
    (100 2K)
    K=5

    thank u so much
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,884
    Thanks
    673
    is this what you're trying to find?

    \sum_{k=5}^{100} (100-2k)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Oct 2008
    Posts
    147
    You can pull out the 100 from the equation, and have
     <br />
9600 - \sum_{k=5}^{100} 2k<br />
    Now you can pull our the 2 from the summation
     <br />
9600-2(\sum_{k=5}^{100} k)<br />
    Now simply solve that summation, which should be easy.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Nov 2008
    Posts
    25
    thank u so much... you are wonderful!
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,807
    Thanks
    697
    Hello, Steph07!

    Evaluate: . \sum^{100}_{k=5}(100-2k)

    We have: . S \;=\;90 + 88 + 86 + \hdots - 96 - 98 - 100

    This is an arithmetic series with:
    . . first term a = 90, common difference d = -2, and n = 146 terms.

    The sum is: . S \;=\;\frac{n}{2}\bigg[2a + (n-1)d\bigg] \;=\;\frac{146}{2}\bigg[2(90) + 145(-2)\bigg] \;=\;\boxed{-8030}

    Follow Math Help Forum on Facebook and Google+

  6. #6
    Junior Member
    Joined
    Nov 2008
    Posts
    25
    omg, thank u I was still workin on that one.. thank u so much
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Math in title
    Posted in the LaTeX Help Forum
    Replies: 1
    Last Post: January 21st 2010, 05:17 AM
  2. latex in the title box
    Posted in the LaTeX Help Forum
    Replies: 2
    Last Post: December 26th 2009, 02:27 AM

Search Tags


/mathhelpforum @mathhelpforum