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Math Help - solve Polynominal question - easy

  1. #1
    Member Awsom Guy's Avatar
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    solve Polynominal question - easy

    X^3-1/X+2

    This says X to the power of 3, subtract 1, divided by, X plus 2.
    Thanks I coudn't even start this question because all the other question had three or more top numbers like X^3+2X^2-13X+10.
    I need this help.
    Thanks for the help....
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  2. #2
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    Quote Originally Posted by Awsom Guy View Post
    X^3-1/X+2

    This says X to the power of 3, subtract 1, divided by, X plus 2.
    Thanks I coudn't even start this question because all the other question had three or more top numbers like X^3+2X^2-13X+10.
    I need this help.
    Thanks for the help....
    What are you meant to be doing with this expression? Please post the question exactly as it's written in wherever you got it from.
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  3. #3
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    Hi

    Well are you trying to solve for X when that equation is equal to ZERO?

    e.g. ((X^3)-1)/(X+2) = 0

    If so then all you need to do is solve for (X^3)-1 = 0, because if the top line is zero then the whole fraction is zero.

    Therefore solving that equation will give an answer of X=1.

    Also there are two more solutions (it is a cubic).In order to get those you need to do long division on (X^3)-1 with (X-1), which will then give an equation of ((X^2)-X+1). And when you solve this for zero you will get two complex roots 0.5+0.86i and 0.5-0.86i


    Hope this helps
    Last edited by kanu999; July 22nd 2009 at 04:08 PM.
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  4. #4
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    Quote Originally Posted by Awsom Guy View Post
    X^3-1/X+2

    This says X to the power of 3, subtract 1, divided by, X plus 2.
    Thanks I coudn't even start this question because all the other question had three or more top numbers like X^3+2X^2-13X+10.
    If this is a question about how to do polynomial division, you should think of the numerator as being x^3 + 0x^2 + 0x - 1. Then it will have "three or more top numbers" (even though some of them are zero), and you can divide it by x+2 in just the same way as you would if it was something like " X^3+2X^2-13X+10".
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