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Math Help - Adding and Subtracting Algebraic Fractions

  1. #1
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    Adding and Subtracting Algebraic Fractions

    Hi how do you solve these two questions? Simplify the following:


    (both attached)

    Thanks.
    Attached Thumbnails Attached Thumbnails Adding and Subtracting Algebraic Fractions-untitled.jpg   Adding and Subtracting Algebraic Fractions-f.jpg  
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  2. #2
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    Re: Adding and Subtracting Algebraic Fractions

    Hey jeremyjezzanba.

    You can't really solve these equations since there is nothing to compare them to: comparisons need either an inequality (like > or <) or an equality (i.e. = ).

    You just have an expression which means nothing: if you make it equal to something or give it an inequality then this is a different thing but as it stands you can't solve anything.

    You can simplify these but that's different: simplifying fractions of A/B + C/D is basically using the rule [AD+BC]/BD. Have you covered this in class before?
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    Re: Adding and Subtracting Algebraic Fractions

    yeh sorry i didn't mean solve i meant simplify. We have very briefly but it is a broad topic so this exact part hasn't been covered. If i could just get a worked example of them i would be able to work others out, thanks.
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  4. #4
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    Re: Adding and Subtracting Algebraic Fractions

    So for the first one you have 1/(x-5) - 3/(x+4) = [x+4 - 3(x-5)]/[(x+4)(x-5)] = (19 - 2x)/[(x-4)(x-5)]

    Edited: For typo
    Last edited by chiro; October 6th 2012 at 05:27 PM. Reason: typo
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  5. #5
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    Re: Adding and Subtracting Algebraic Fractions

    thankyou but it is X+4 and it is not the right answer
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  6. #6
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    Re: Adding and Subtracting Algebraic Fractions

    Quote Originally Posted by jeremyjezzanba View Post
    thankyou but it is X+4 and it is not the right answer
    chiro made a typo, but you should be able to take what was provided, change x-4 to x+4 and combine the fractions yourself
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    Re: Adding and Subtracting Algebraic Fractions

    yes thanks I got it in the end but Still can't work out the second question
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    Re: Adding and Subtracting Algebraic Fractions

    note that x-2 = -(2-x)
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    Re: Adding and Subtracting Algebraic Fractions

    I understand that I just don't get the method
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  10. #10
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    Re: Adding and Subtracting Algebraic Fractions

    \frac{3}{x-2} + \frac{4}{2-x} = \frac{3}{x-2} + \frac{-4}{-(2-x)}
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  11. #11
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    Re: Adding and Subtracting Algebraic Fractions

    Adding and Subtracting Algebraic Fractions-dsfdfs.jpg


    is this correct?
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  12. #12
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    Re: Adding and Subtracting Algebraic Fractions

    no.

    \frac{3}{x-2} + \frac{4}{2-x} = \frac{3}{x-2} + \frac{-4}{-(2-x)} = \frac{3}{x-2} + \frac{-4}{x-2} = \frac{3-4}{x-2} = \frac{-1}{x-2}
    Thanks from jeremyjezzanba
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