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Math Help - polynomial

  1. #1
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    Smile polynomial

    The remainder when -4x^2 + 2x + 7 is divided by (x - c) is -5. Find a possible whole number value of c.
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  2. #2
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    Well... why not divide and see what you get! Its too complicated for me to write out but I get x - c goes into -4x^2 +2x +7, -4x + (2-4c) times with a remainder of 7+(2 - 4c)*c

    Can you figure it out from there?
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  3. #3
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    Smile

    Not really...I'd rather someone show me a complete worked out solution (I'd understand how to do this if the -c in x - c was a number). And be quick please everybody... the faster I get a response the more math I can do!

    Sorry, if that seemed rude anyway, I'd appreciate any more responses.
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  4. #4
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    Also, I don't think you need to divide -4x^2 + 2x + 7 by the x - c to find out the answer. I am looking for this other way.
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  5. #5
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    The remainder theorem says: If a polynomial p(x) is divided by a linear factor x - a, then the remainder is equal to p(a)

    So, we have the solve the equation: p(a) = -5 \ \iff \ -4a^2+2a + 7 = -5

    Move -5 to the other side to get: -4a^2 + 2a + 12 = 0

    This is a simple, factorable quadratic. See if you can go on from here.
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  6. #6
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    Unhappy

    I don't understand.
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  7. #7
    Grand Panjandrum
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    Quote Originally Posted by tyco3c View Post
    I don't understand.
    Quote what you are refering to so that we know what help you need.

    CB
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