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    Any One Do A2 Maths C4??

    the question is

    given that f(x) = 2xcubed + 9xsqaured + 10x + 3


    part a is easy just says show that -3 is a root of F(x), if you sub -3 in as x you get 0.

    but part b says

    Express 10/f(x) as partial fractions

    now when theres a quadractic as the denominator thats fine i can split them up, but i dont know how to factorise that cubic equation to get 3 seperate fractions, any help?? been stuck on this all day.

    14 Comments

    15 years ago i coulda told you but, got drunk far too many times to remember all this sry . and gl

    Mate you've got the factor, -3, so divide the cubic by (x+3) and get a quadratic.

    I only do AS but I'm guessing that would work.

    Banned

    ^ maybe
    and
    Express 10/f(x) as partial fractions

    Are you sure its 10 divided by the f(x) don't usually see that sort of question.

    LOL, i can help -
    you said -3 is a root of x, right?
    so immediately you can factorise to become (x+3)(whatever)
    Use long division or other to get the "whatever". It will DEFINATELY work becos -3 will flush in perfectly -its a root.
    EDIT: Ahh someone above said it already

    I'm no help, just thought you should know i hate your avatar.

    Good luck finding the answer.

    Original Poster

    Pryd4 i think you may be right, figures i got a E in AS, thats defiantly the question.

    Banned

    Hmm

    so using the factor -3?

    if you do this you got it yeah?

    http://img132.imageshack.us/img132/6805/lolkq5.jpg

    Artonox;4264578

    LOL, i can help -you said -3 is a root of x, right?so immediately you can … LOL, i can help -you said -3 is a root of x, right?so immediately you can factorise to become (x+3)(whatever)Use long division or other to get the "whatever". It will DEFINATELY work becos -3 will flush in perfectly -its a root. EDIT: Ahh someone above said it already



    Beat you to it

    Original Poster

    yhhh i did it thanks guys,

    i ended up with after findind a.b.c

    1/x+3 + 8/2x+1 - 5/x+1

    rep left for the help

    Banned

    Artonox;4264578

    LOL, i can help -you said -3 is a root of x, right?so immediately you can … LOL, i can help -you said -3 is a root of x, right?so immediately you can factorise to become (x+3)(whatever)Use long division or other to get the "whatever". It will DEFINATELY work becos -3 will flush in perfectly -its a root. EDIT: Ahh someone above said it already



    Its a factor of X not a root i think

    wazb;4264639

    yhhh i did it thanks guys,i ended up with after findind a.b.c1/x+3 + … yhhh i did it thanks guys,i ended up with after findind a.b.c1/x+3 + 8/2x+1 - 5/x+1rep left for the help



    No problem :thumbsup:

    Original Poster

    Conscept;4264644

    Its a factor of X not a root i think





    its defo a root, question says ahow that -3 is a root of f(x)

    Conscept;4264644

    Its a factor of X not a root i think



    lol being nitpicky now arn't we :-D
    I say root because if you draw the graph, it will intersect y=0 at 3 places - they are called roots.
    Or we could call them your way, namely a factor of f(x) because it goes in with no remainders, like 2 is a factor of 4.

    Banned

    wazb;4264686

    its defo a root, question says ahow that -3 is a root of f(x)


    Oh my bad, haha silly me

    Least you got it done
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