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Math Help - I need help!

  1. #1
    Newbie
    Joined
    Mar 2008
    Posts
    3

    I need help!

    I had 5 questions, i wrote em up in photoshop i thought it would be easier.

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  2. #2
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
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    78

    Here is #2

    we know that

    x-y=24 \mbox{ and } A=xy

    We want to minimize A

    subbing the first into the second we get...

    A=(y+24)y=y^2+24y

    Since we want the minimum value we need to find the vertex of the parabola.

    There are a few different ways. Since it is symmetric about its vertex the vertex is half way between its intercepts -24 and 0 so at -12

    or we could use the vertex fromula

    y=\frac{-b}{2a}=\frac{-24}{2(1)}=-12

    Now that we know y we can solve for x

    x-(-12)=24 \iff x=12

    so the minimum product is x \cdot y =(12)(-12)=-144
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