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Math Help - Having trouble with high school algebraic fractions

  1. #1
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    Having trouble with high school algebraic fractions

    Hi,

    I'm having a bit of trouble with the work I was assigned by my teacher. The problem goes:

    1/(3-x) + (2x-5)/(x-7x+12)

    The common denominator is supposed to be (x-3)(x-4) and the answer is supposed to be x-1/cd. The problem is that two of the common denominator terms have the same variables but different signs, namely (3-x) and (x-3). I'm supposed to simplify out one of those factors and then switch the operator between the fractions so that this becomes a subtraction problem. The thing is I don't know which one of the factors to remove, which factor to multiply the numerator by, and how I should proceed in general. Can anyone help me?

    Thanks!
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  2. #2
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    Re: Having trouble with high school algebraic fractions

    Quote Originally Posted by KevinShaughnessy View Post
    1/(3-x) + (2x-5)/(x-7x+12)
    The common denominator is supposed to be (x-3)(x-4) and the answer is supposed to be x-1/cd.

    Note that \frac{1}{(3-x)}+\frac{2x-5}{x^2-7x+12}=\frac{2x-5}{(x-3)(x-4)}-\frac{1}{(x-3)}.

    Now can you see LCD?
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  3. #3
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    Re: Having trouble with high school algebraic fractions

    You need to know that 3- x= -(x- 3).
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  4. #4
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    Re: Having trouble with high school algebraic fractions

    Awesome, it makes sense now. Thanks guys, I really appreciate it!
    Last edited by KevinShaughnessy; January 20th 2013 at 01:22 PM.
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