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Math Help - polynomial division and remainder theorem

  1. #1
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    polynomial division and remainder theorem

    Hi;

    use remainder theorem to find the remainder of (3x^4 - 5x^2 - 20x -8) / (x + 1).


    When using remainder theorem I get remainder -33

    and with long division I get remainder 10 which I think is the right answer.

    Not sure why I'm getting -33 with remainder theorem
    What am I missing?


    Thanks.
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  2. #2
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    Re: polynomial division and remainder theorem

    The correct answer is 10. Post your working.
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  3. #3
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    Re: polynomial division and remainder theorem

    ...

    Code:
    -1] ... 3 ... 0 ... -5 ... -20 ... -8
    
    .............-3 ....3.......2 ... 18
    ---------------------------------------
    
    .......3.....-3....-2.....-18 ... 10
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  4. #4
    Senior Member eumyang's Avatar
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    Re: polynomial division and remainder theorem

    Quote Originally Posted by anthonye View Post
    Hi;

    use remainder theorem to find the remainder of (3x^4 - 5x^2 - 20x -8) / (x + 1).


    When using remainder theorem I get remainder -33

    and with long division I get remainder 10 which I think is the right answer.

    Not sure why I'm getting -33 with remainder theorem
    What am I missing?


    Thanks.
    Using the remainder theorem,
    f(-1)
    = 3(-1)^4 - 5(-1)^2 - 20(-1) - 8
    = 3 - 5 + 20 - 8
    = 10
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  5. #5
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    Re: polynomial division and remainder theorem

    Yeah I got it thank you.
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