Thread: mathematics polynomial long division

  1. #1
    essence of digital xddxogm3's Avatar
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    mathematics polynomial long division

    I think I found an error in my math book.
    I'm using polynomial long division to calculate the slant asymptote. can someone check this to see if i'm correct.

    the book says the following.

    (x^2-4x-5)/(x-3)=x-1+(8/x-3)

    I think it should be

    (x^2-4x-5)/(x-3)=x-1-(8/x-3)

    note the only difference is the subtraction/addition of the remainder fractional value.
    who is correct? (me or book)
    "Hence to fight and conquer in all your battles is not supreme excellence;
    supreme excellence consists in breaking the enemy's resistance without fighting."
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  2. #2
    C++ Witch laserlight's Avatar
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    The simplest way to check is to plugin values.

    Let's try x=7
    (x^2-4x-5)/(x-3) = 16/4 = 4
    x-1+(8/(x-3)) = 8
    x-1-(8/(x-3)) = 4

    The book must be wrong, while you are probably correct.
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    Obsessed with C chrismiceli's Avatar
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    I am not in the highest forms of math, but for polynomial division, isn't there something called synthetic division: http://www.purplemath.com/modules/synthdiv.htm . I don't know if that is what you want to use or if you are even allowed, but if you want to expand your math concepts, look into it.
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  4. #4
    essence of digital xddxogm3's Avatar
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    yes, i know about synthetic division.
    i was almost certain i was correct, but wanted to make sure, that i was not making a mistake somewhere, with forgeting some obscure special case rule.
    this book i'm using is horrible. it doesn't have all the answers, and some of the text has been proven to be inaccurate.
    thank you both
    "Hence to fight and conquer in all your battles is not supreme excellence;
    supreme excellence consists in breaking the enemy's resistance without fighting."
    Art of War Sun Tzu

  5. #5
    Crazy Fool Perspective's Avatar
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    I think some high school math/sci books intentionally give false answers to every nth numeric answer. It makes it easier for the teacher to see if someone is using the back of the book a little too much

  6. #6
    essence of digital xddxogm3's Avatar
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    the error was in the actual lesson walk through.
    so it was teaching me the wrong way.
    "Hence to fight and conquer in all your battles is not supreme excellence;
    supreme excellence consists in breaking the enemy's resistance without fighting."
    Art of War Sun Tzu

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