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Math Help - Solve this!

  1. #1
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    Nov 2008
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    Solve this!

    I want to solve this equation for x:

    ax^2+cx^(1.5)=b

    But this is not as easy as it seemed. Perhaps someone can help.

    Gr.
    Dirk
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  2. #2
    MHF Contributor
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    France
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    Quote Originally Posted by dirk_de_groof View Post
    I want to solve this equation for x:

    ax^2+cx^(1.5)=b

    But this is not as easy as it seemed. Perhaps someone can help.

    Gr.
    Dirk
    Hello Dirk
    ax^2+cx\sqrt{x}=b
    cx\sqrt{x}=b-ax^2
    c^2x^3=(b-ax^2)^2 which leads to a fourth degree polynomial equation
    I do not know if this is of any help for you
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  3. #3
    Newbie
    Joined
    Nov 2008
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    finding the roots of a 4th degree polynomial

    Thank you!
    But now I need to find the roots of this 4th degree polynomial.. Does anyone know a method with not too much computational load? The polynomial looks like this:


    au^4+cu^3-b

    Where:
    \sqrt{x}=u

    in:
    ax^2+cx\sqrt{x}-b

    Gr
    Dirk
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  4. #4
    MHF Contributor
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    France
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    There is a method called Ferrari's method but maybe a little bit difficult
    Méthode de Ferrari - Wikipédia

    Sorry for the French version, I could not find the English one
    Anyway mathematics are a universal language !
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