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!

A basic function question - with a strange absolute value placement

  1. May 21, 2010 #1
    1. The problem statement, all variables and given/known data

    If f(x) is equal to...

    x+9 if x<-3
    -2x if |x|[tex]\leq[/tex] 3
    -6 if x > 3


    2. The attempt at a solution

    The first and third "segments" of when the function is defined as being x+9 and -6 are pretty straightforward to me, however I am unaware of the significance of the placement of the absolute value of x in the middle if statement of when the function is equal to -2x. Is it significant at all? Does this imply this function is undefined when -3 < x < 0? Or is it, as my initial hunch was, really just some type of a distraction?
     
  2. jcsd
  3. May 21, 2010 #2

    Mark44

    Staff: Mentor

    |x| <= 3 is equivalent to -3 <= x <= 3, so your hunch that this is a distraction is wrong.
     
  4. May 21, 2010 #3
    [tex]
    0 \le \left| x \right| \le a \; \Leftrightarrow \; -a \le x \le a
    [/tex]
     
  5. May 21, 2010 #4
    Thank you. I didn't choose my word "distraction" cautiously enough. Since the statements you both posted are equivalent - that was indeed what I needed to know.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: A basic function question - with a strange absolute value placement
Loading...