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Homework Help: Partial derivative: please check work

  1. Apr 16, 2014 #1

    939

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    1. The problem statement, all variables and given/known data

    (50 - x - y)(x+y) - x - ((y^2)/2))

    simplified: 50X - X^2 - XY - 50Y - XY - Y^2 - X - ((Y^2)/2)


    2. Relevant equations

    50X - X^2 - XY - 50Y - XY - Y^2 - X - ((Y^2)/2))

    3. The attempt at a solution

    for x:
    49 - 2x - 2y

    for y:
    50 - 2x - 3y

    The book has the same, except -1x and -1y (i.e. 49 - 1x - 2y) and (50 - 1x - 3y). Why is this?
     
  2. jcsd
  3. Apr 16, 2014 #2

    haruspex

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    I agree with your answers, except you have a sign wrong in the 'simplified' equation (which gets corrected in the final answer).
     
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