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Math Help - HELP!!!---find absolute extrema of...

  1. #1
    Member sluggerbroth's Avatar
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    HELP!!!---find absolute extrema of...

    Find absolute extrema of...
    f(x,y)=xy-2x-y+6 on closed triangular region with vertices (0,0), (0,8) and (4,0). I need to know what the etremum are and if max or min and at what points these occur.
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  2. #2
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    Re: HELP!!!---find absolute extrema of...

    What you "need to know" is how to find max and min!

    Whoever gave you this problem clearly expects you to know that if a max or min occurs in the interior of a region in two dimensions the two partial derivatives must both be 0. Of course, the max and/or min might be on a boundary. The boundary consists of the three line segments bounding the triangle. Write each with y as a function of x. If a max or min occurs in the interior of a segment, must be where the derivative of y with respect to x 0. Finally, a max or min may occur at the boundary of an interval and those boundaries are the three vertices of the triangle.
    Last edited by HallsofIvy; March 17th 2013 at 02:18 PM.
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  3. #3
    Member sluggerbroth's Avatar
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    Re: HELP!!!---find absolute extrema of...

    thanks but i am going to need more guidance? help again please?
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    Re: HELP!!!---find absolute extrema of...

    I am confused- this is a fairly standard "Calculus of Several Variables". Are you saying you do not know how to find a partial derivative?
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  5. #5
    Member sluggerbroth's Avatar
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    Re: HELP!!!---find absolute extrema of...

    Partial derivative I can handle but how to deal with boundry?
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