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Proving the definition of abs. value

  1. Jan 23, 2005 #1
    I need to show that the absolute value of x = max {x, -x}. Of course I know this is true, but I must show this. How would I go about doing such a thing?
  2. jcsd
  3. Jan 23, 2005 #2


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    The absolute value is always positive, right?
    Use that fact.
  4. Jan 23, 2005 #3


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    BTW,a definition cannot be proved...

    Lemmas,theorems,properties,propositions,corolaries,but not definitions...

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