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: Another group theory question

  1. Nov 9, 2006 #1
    Could you also help me start this question

    show that if a^2 = e for all a in G then G must be commutative. (where e is the identity)

    thanks
     
  2. jcsd
  3. Nov 9, 2006 #2

    0rthodontist

    User Avatar
    Science Advisor

    What does aabb equal? What does abab equal?
     
  4. Nov 9, 2006 #3
    umm ok .. so i get that aabb must also =e .. but im not sure how to get abab
     
    Last edited: Nov 9, 2006
  5. Nov 9, 2006 #4

    JasonRox

    User Avatar
    Homework Helper
    Gold Member

    Just show that ab = ba.

    That's what you're doing. Start from there.
     
  6. Nov 9, 2006 #5

    0rthodontist

    User Avatar
    Science Advisor

    It's (ab)(ab), so you know aabb = abab. Can you finish that?
     
  7. Nov 12, 2006 #6
    thanks :).. i got it now
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook