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Homework Help: I need help with this homework problem

  1. Oct 14, 2012 #1
    1. The problem statement, all variables and given/known data

    Find three positive numbers whose sum is 12 and the sum of whose squares is as small as possible.

    2. Relevant equations

    3. The attempt at a solution

    I don;t even know how to start this one, this is a section from partial derivatives on the max and mins. Please i need guidance through this exercise. Thank you!
  2. jcsd
  3. Oct 14, 2012 #2


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    Hi ScienceGeek24! :smile:

    Start by calling the three numbers x y and z, and putting f(x,y,z) = x2 + y2 + z2 :wink:
  4. Oct 14, 2012 #3
    In addition to tiny-tim's good first idea, how about using the fact that you know that x+y+z=12, so you know what z is in terms of x and y - then you only have a 2D problem to solve.
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