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Math Help - Quadratic

  1. #1
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    South AFrica
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    Quadratic

    Hi Everybody. First technical post on here, need help with a high school grade10 Algebra question included in a section on Quadratic equations.
    I've never seen a q like this so really not sure how to approach it.

    Express b in terms of j
    8 - {(b2 - 64)j} + b = 181/2


    Tried several angles of expanding the expressions but can't get down to anything that helps me simplify further.
    Here are some of the approaches I tried.

    1.
    - (b+8)(b-8)j + (b+8) = 181/2
    (b+8)(b-8)j - (b+8) = - 181/2
    (b+8).[(b-8)j - 1] = - 181/2

    Not sure what to do next. Tried a few other approaches but still can't see I'm on the right track.

    Any suggestions?
    (and I also hope this doesn't get demoted down to the "normal" Algebra section)

    Thanks.
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  2. #2
    MHF Contributor

    Joined
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    Tejas
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    Re: Quadratic (??) equation

    But it IS "normal" Algebra, this section is for Advanced algebra, such as the study of vector spaces and groups.

    Since we are solving an equation with "$b$" as the variable, we can re-write it like so:

    $(-64j)b^2 + b + (8 - 64j - \sqrt{18}) = 0$

    This is a quadratic equation in $b$, with solution:

    $b = \dfrac{-1 \pm \sqrt{1 + (4)(64j)(8-64j -\sqrt{18})}}{-128j}$

    It is unclear from your problem whether or not $j$ is intended to be a square root of -1.
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  3. #3
    Newbie
    Joined
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    South AFrica
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    Re: Quadratic

    Hi there, thanks for the help.
    Looking back at the rules of the forum and I must admit, I did not check the section rules properly.
    As a newbie, I'm using my ignorance card now, and promising to never let it happen again.
    Sorry about that dudes, and thanks for the answer.
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