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Thread: Related Rates... I think

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    Lively Member MHENK's Avatar
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    Related Rates... I think

    Suppose i have a closed box, the volume of this box is fixed, say, 60in^3.

    The material for the top and the bottom of the box cost twice as much as the material for the sides. How would I go about minimizing the costs. I know it has something to do with taking the derivative = 0, but other than that, i'm stumped... Any help here would be much appreciated.
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    transcendental analytic kedaman's Avatar
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    hints:
    1. make a function height->cost
    2. assume width and length are equal (unless you have to prove that they must be to maximize bottom/top area)
    3. the second derivative has to be positive as well (otherways its a local maximum)
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