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Thread: Algebraic Fractions

  1. #1
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    Question Algebraic Fractions

    Hi All,

    Can someone tell me why:

    2a/3b x 6/a2b = 4/ab2

    Why does 6 become 4? Is this to do with cancelling common factors?

    This is why I dislike the book Engineering Mathematics by Stroud for this very reason. It will give you some really basic example to start with then ask you to solve an equation when they haven't explained the specifics properly.

    Thanks


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  2. #2
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    Re: Algebraic Fractions

    Quote Originally Posted by mc444 View Post
    Hi All,

    Can someone tell me why:

    2a/3b x 6/a2b = 4/ab2

    Why does 6 become 4? Is this to do with cancelling common factors?

    This is why I dislike the book Engineering Mathematics by Stroud for this very reason. It will give you some really basic example to start with then ask you to solve an equation when they haven't explained the specifics properly.

    Thanks


    $\dfrac{2a}{3b} \cdot \dfrac{6}{a^2b} = \dfrac{2a \cdot 6}{3b \cdot a^2b} = \dfrac{2a \cdot 2 \cdot 3}{3b \cdot a \cdot ab} = \dfrac{2\cancel{a} \cdot 2 \cdot \cancel{3}}{\cancel{3}b \cdot \cancel{a} \cdot ab} = \dfrac{4}{ab^2}$
    Thanks from topsquark
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  3. #3
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    Re: Algebraic Fractions

    Skeeter you legend. Thanks for that. This has cleared a lot of confusion up!
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  4. #4
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    Re: Algebraic Fractions

    Equivalently, 2* 6= 12 and 12/3= 4.
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    Re: Algebraic Fractions

    Quote Originally Posted by mc444 View Post
    Hi All,

    Can someone tell me why:

    2a/3b x 6/a2b = 4/ab2

    Why does 6 become 4? Is this to do with cancelling common factors?

    Oh, those sides are equal, but not why you think they are. When you write/type them out horizontally,
    place grouping symbols around these needed denominators as such:

    2a/(3b) x 6/(a2b) = 4/(ab2)
    Thanks from topsquark
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