Results 1 to 5 of 5

Math Help - please help

  1. #1
    Junior Member
    Joined
    Oct 2013
    From
    nevada
    Posts
    58

    please help

    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Oct 2009
    Posts
    5,502
    Thanks
    765

    Re: please help

    Finding C and D is called partial fraction decomposition. See an example here and also in section Examples on the same page.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,307
    Thanks
    1284

    Re: please help

    You can do that simply by adding the fractions as indicated: \dfrac{C}{x- 3}+ \dfrac{D}{x+ 8}= \dfrac{C(x+8)}{(x- 3)(x+ 8)}+ \dfrac{D(x- 3)}{(x-3)(x+ 8)} = \dfrac{(C+D)x+ (8C- 3D)}{(x- 3)(x+ 8)}= \dfrac{4x- 23}{(x- 3)(x+ 8)}
    Do you see that you must have C+ D= 4 and 8C- 3D= -23?

    Surely you see that (x- 3)(x+ 8)= x^2+ 5x- 24?
    Last edited by HallsofIvy; November 13th 2013 at 07:54 AM.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Nov 2010
    Posts
    1,765
    Thanks
    683

    Re: please help

    Edit: HallsofIvy corrected the post, so this one is unnecessary.
    Last edited by SlipEternal; November 13th 2013 at 07:52 AM.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,307
    Thanks
    1284

    Re: please help

    Just before I did! Thanks.

    Although I don't think I got it completely corrected until after you removed your correction!
    Last edited by HallsofIvy; November 13th 2013 at 07:55 AM.
    Follow Math Help Forum on Facebook and Google+


/mathhelpforum @mathhelpforum