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Math Help - Adding Rational Expressions

  1. #1
    Junior Member
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    Adding Rational Expressions

    I can't get the same answer as the book in this one:

    \frac{n^2+4n-3}{n^2-16}+\frac{4-3n}{3n-12}

    the answer i ended up with:

    \frac{3n+3}{3(n+4)(n-4)}

    book answer:

    \frac{4n+7}{3(n+4)(n-4)}
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  2. #2
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    Hello, t-dot!

    If you'd show your work, we could find your error . . .


    [tex] \frac{n^2+4n-3}{n^2-16}+\frac{4-3n}{3n-12}

    We have: . \frac{n^2 + 4n - 3}{(n+4)(n-4)} + \frac{4-3n}{3(n-4)}

    Get a common denominator: . {\color{blue}\frac{3}{3}}\cdot\frac{n^2 + 4n-3}{(n+4)(n-3)} + \frac{4-3n}{3(n-4)}\cdot{\color{blue}\frac{n+4}{n+4}}

    . . = \;\frac{3(n^2+4n-3) + (4-3n)(n+4)}{3(n+4)(n-4)} \;=\;\frac{3n^2 + 12n - 9 + 4n + 16 - 3n^2 -12n}{3(n+4)(n-4)}<br />

    . . = \;\frac{4n+7}{3(n+4)(n-4)} . . . . There!

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