1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Proof of an expression involving absolute value

  1. Dec 17, 2011 #1
    1. The problem statement, all variables and given/known data

    Prove: for any real number x, -|x|[itex]\leq[/itex]x[itex]\leq[/itex]|x|.

    2. Relevant equations

    Only the definition of absolute value is allowed.

    3. The attempt at a solution

    Don't even know where to start
     
  2. jcsd
  3. Dec 17, 2011 #2
    First prove -lxl≤x then prove x≤lxl
     
  4. Dec 18, 2011 #3

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Also consider breaking the problem into two cases, where x ≥ 0 and x < 0.
     
    Last edited: Dec 18, 2011
  5. Dec 18, 2011 #4
    pretty much what mtayab and LCKurtz said
    first take x greater than zero, take x less than zero and take x equal to zero

    this method is called a proof by exhaustion
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Proof of an expression involving absolute value
  1. Absolute value proof (Replies: 6)

Loading...