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Math Help - Polynomial factoring

  1. #1
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    Polynomial factoring

    Hey guys.. having a problem with this.. I feel like the step I am missing is pretty basic, so you should be able to spot it quickly.. I am having a problem with my long division.

    Here it is in paint:

    Polynomial.jpg picture by AKelsoY - Photobucket
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  2. #2
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    on your last two lines ...

    x^2 - 1
    x^2 + x
    --------
    -x - 1

    now ... x+1 will go into -x-1 how many times?
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  3. #3
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    -1?

    So it will be 2x^2+x-1?
    Last edited by Slipery; January 28th 2009 at 02:05 PM. Reason: retracting my statement
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  4. #4
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    Quote Originally Posted by Slipery View Post
    -1?

    So it will be 2x^2+x-1?
    you check it ...

    is (x+1)(2x^2+x-1) = 2x^3 + 3x^2 - 1 ?
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  5. #5
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    Yup! thanks
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  6. #6
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    I got it..

    I am having another problem though..

    I cannot factor (2x^2 - 1)??? I have tried many combinations.. I have been trying this for 20 minutes, so its a bit frustrating

    I hope its not something as easy as leaving the two in front of the bracket. This is for a question where I have to solve the equation. How would having a 2 in front of the bracket affect my zero?..

    The question is 'Solve 2x^3+6x^2-x-3= 0'
    So I have (x+3)(2x^2-1)

    Now what? =(
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  7. #7
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    if you solve 2x^2 - 1 using the quadratic formula:

    \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

    the roots come out to be:

    (x + \frac{\sqrt{2}}{2}) & (x - \frac{\sqrt{2}}{2})


    Hope this helps
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