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Math Help - Quadratics with equal roots.

  1. #1
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    Quadratics with equal roots.

    I think this is the right place to post this, I'm in England and don't know how the American schooling system works, but here goes:

    "Find the values of k for which kx(sq)+8x+k = o has equal roots."

    I know that for this equation to have equal roots the discriminant must equal zero, so:

    b(sq)-4ac = 0

    Putting numbers into this I get:

    64-4k(sq) = 0

    64=4k(sq)

    This is where i get stuck - do I first square root each side, giving:

    8=4k

    and getting an answer 2, or do I first divide each side by 4, giving:

    16=k(sq)

    and getting 4 as the answer?

    So to sum up, do I square root first, or simplify first?

    Thanks in advance.
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  2. #2
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    Order of operations, if you had a value for k, would be to square first, then multiply by 4.
    To undo it then (solving for k), you need to divide by 4 first, then square root.
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  3. #3
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    thank you : )

    how do I properly "thank" you?

    (I'm new here)

    -EDIT-

    Don't worry, found it : )
    Last edited by NotanotherNickname; October 29th 2008 at 11:32 AM. Reason: answered own question
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