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Math Help - Reducing question

  1. #1
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    Reducing question

    The problem was 4ab^3 / a^3 divided by -12a^4b / ab^2

    I know you have to flip the second fraction, then multiply, but I don't understand how you get from that answer to the real answer, -b^4 / 3a^4 well, at least the answer key we were given said that. Any help would be much appreciated
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  2. #2
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    Quote Originally Posted by onetreehill56 View Post
    The problem was 4ab^3 / a^3 divided by -12a^4b / ab^2

    I know you have to flip the second fraction, then multiply, but I don't understand how you get from that answer to the real answer, -b^4 / 3a^4 well, at least the answer key we were given said that. Any help would be much appreciated
    \frac{ \frac{4ab^3}{a^3} }{ -\frac{12a^4b}{ab^2} } = \frac{4ab^3}{a^3} \cdot -\frac{ab^2}{12a^4b}

    = -\frac{4ab^3 \cdot ab^2}{a^3 \cdot 12a^4b}

    = -\frac{4a^2b^5}{12a^7b}

    = -\frac{b^4 \cdot 4a^2b}{3a^5 \cdot 4a^2b}

    = -\frac{b^4}{3a^5}
    so your given answer was off by a factor of a.

    -Dan
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