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Math Help - More Partial Fractions Help

  1. #1
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    More Partial Fractions Help

    Well, I took a quiz earlier this week, and I didn't do so hot on it (59). One of the questions I missed was a partial fraction question. Under normal circumstances I wouldn't be on here asking about it, but we have a problem similar to the one seen on the quiz (which I will show you in a moment) on the practice test, and there's a chance it could be on the test this coming Friday.

    \frac{1}{4x^2-9}

    ~~~~~~~

    Obviously this fraction is improper, so I divided it out to get

    1+\frac{4x^2+0x-9}{4x^2+0x-9}.

    I got stuck after this point. When I reviewed it after I turned in the quiz. \frac{4x^2+0x-9}{4x^2+0x-9} cancels out, leaving 1 + 1, which equals two. I'm thinking this is wrong, but this is how my thinking went about it, at least on the quiz.

    Just now when I looked at it again, I realized it was actually 1 + \frac{-9}{4x^2+0x-9}. But I'm still unsure as to how to go about doing it from there.

    I appreciate any and all help given to this problem.
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  2. #2
    Math Engineering Student
    Krizalid's Avatar
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    Note that (2x+3)-(2x-3)=6. (Pretty obvious but useful.) Now why did I do this? 'cause you can replace it in the numerator and split the original ratio into two fractions.
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  3. #3
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    I see how you were able to factor that expression, but I have absolutely no idea where you got the six from.

    EDIT: Never mind, just figured it out.
    Last edited by mathgeek777; March 30th 2008 at 05:53 AM. Reason: Figured the question out.
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