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Homework Help: Inequality proof problem

  1. Aug 22, 2010 #1
    1. The problem statement, all variables and given/known data

    l lxl - lyl l =< lx-yl

    2. Relevant equations


    3. The attempt at a solution

    how do i proof this? give me a start please, should i use definition absolute values and consider all of the cases? or use triangle inequality(but i can't figure out how)
  2. jcsd
  3. Aug 22, 2010 #2
    Re: inequality

    hey i get it, use x=(x-y)+y
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