1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Complex numbers

  1. Sep 10, 2010 #1
    OK, in my book we have an inequality ||z|-|w||[tex]\leq[/tex]|z+w|[tex]\leq[/tex]|z|+|w| then from here it simply states, "Replacing w by -w here shows that ||z|-|w||[tex]\leq[/tex]|z-w|[tex]\leq[/tex]|z|+|w|.

    How do we know that???
    is |z+w|=|z-w|?? Note that z and w are complex numbers.
     
  2. jcsd
  3. Sep 10, 2010 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    No, |z+w| is NOT equal to |z-w|. Your first inequality is true for all w. Therefore it also must be true for -w. Substitute '-w' everywhere you see 'w' in the first inequality.
     
  4. Sep 10, 2010 #3
    Thanks alot Dick, again. You rock
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook