Results 1 to 3 of 3

Math Help - More help with Binomials

  1. #1
    Newbie
    Joined
    May 2008
    Posts
    8

    More help with Binomials

    Well after isomorphism helped get me sorted out the other day I thought I had these Binomials licked BUT!!!!

    When I tried this one I couldn't seem to get the right answer

    Find the term x^44 in the following

    (x^2 - 1/sq root x)^27

    So thought I was doing well getting

    this as the general term

    (27 over r) ( x^2n-2r ) . (-x^-1/2r)

    and the solving for r ie 5/2r = 27 but then of course r works out really ugly.

    If someone prepared to have a go at helping I would be grateful
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor red_dog's Avatar
    Joined
    Jun 2007
    From
    Medgidia, Romania
    Posts
    1,252
    Thanks
    5
    \displaystyle T_{k+1}=(-1)^kC_{27}^k(x^2)^{27-k}\left(x^{-\frac{1}{2}}\right)^k=(-1)^kC_{27}^kx^{\frac{108-5k}{2}}
    Then \displaystyle \frac{108-5k}{2}=44\Rightarrow 5k=20\Rightarrow k=4
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    May 2008
    Posts
    8
    Thanks

    If the two components are different which one does one use when solving for r. Do you have nay general tips since I think that's the part I am struggling with?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Sum of binomials
    Posted in the Number Theory Forum
    Replies: 4
    Last Post: March 4th 2010, 06:30 PM
  2. Sum of binomials
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: February 28th 2010, 10:49 PM
  3. binomials...
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: September 20th 2009, 07:17 PM
  4. Binomials
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: September 17th 2009, 09:54 PM
  5. binomials
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: August 3rd 2005, 06:58 PM

Search Tags


/mathhelpforum @mathhelpforum