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!

Absolute Values

  1. Oct 24, 2005 #1
    An example in my textbook gives

    [tex] \vert \frac{5-x}{5x} \vert \Leftrightarrow \frac {1}{5} (\frac{1}{\vert x \vert}) (\vert x-5 \vert) [/tex]

    Is there something I don't know about absolute values that allows [itex] \vert 5-x \vert [/itex] to become [itex] \vert x-5 \vert [/itex] or is this a mistake in the text?
  2. jcsd
  3. Oct 24, 2005 #2


    User Avatar
    Homework Helper

    What would you say about |x| - |-x|?
  4. Oct 24, 2005 #3
    It would be zero. So [tex] \vert 5 \vert + \vert -x \vert \Longleftrightarrow \vert -5 \vert + \vert x \vert [/tex]

    Thanks for the push.
  5. Oct 24, 2005 #4


    User Avatar
    Homework Helper

    Well yes, but in your case |5-x| doesn't necessarily equal |5| + |-x|, but it does equal |x-5|, as you asked in the first place.
  6. Oct 24, 2005 #5


    User Avatar
    Science Advisor
    Gold Member

    By definition |a|=|-a|. Let a=x-5 and the result is obvious.
  7. Oct 24, 2005 #6
    [tex]\vert x \vert - \vert-x \vert = 0[/tex]

    The absolute value a number simply means that its positive, no matter what. So abs(x) - (abs(-x) would be the same as abs(x) - abs(x). This is actaully quite usfull in the field of programming.
    Last edited: Oct 24, 2005
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Absolute Values
  1. Absolute value (Replies: 4)

  2. Absolute value (Replies: 4)

  3. Absolute values (Replies: 5)

  4. Absolute value (Replies: 2)