Results 1 to 5 of 5

Math Help - True or False hurting my head!!

  1. #1
    Member
    Joined
    Apr 2009
    Posts
    136
    Awards
    1

    True or False hurting my head!!

    Hi all,


    True or False


    If ab Ξ 0 (mod 12) then a Ξ 0 (mod 12) or b Ξ 0 (mod 12). Explain your answer.


    I have nothing. lol.


    Please help if possible
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor arbolis's Avatar
    Joined
    Apr 2008
    From
    Teyateyaneng
    Posts
    1,000
    Awards
    1
    I think it's false. As a counter example, take a=2 and b=6. Clearly ab is congruent to 0 modulo 12, but neither a or b is congruent to 0 modulo 12.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor alexmahone's Avatar
    Joined
    Oct 2008
    Posts
    1,074
    Thanks
    7
    False.

    Counterexample: 4*3 Ξ (mod 12) but neither 4 nor 3 is congruent to 0 mod 12.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Banned
    Joined
    May 2009
    Posts
    471
    Let a=14 and b=18, then ab=252 \equiv0 mod 12 but is either a or b \equiv0 mod 12
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Apr 2009
    Posts
    136
    Awards
    1
    Thanks Guys.

    I can use all of your examples to illustrate that this is incorrect.

    Cheers
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 7
    Last Post: October 5th 2011, 01:45 PM
  2. Replies: 1
    Last Post: October 4th 2011, 03:19 AM
  3. how come false AND false is true?
    Posted in the Discrete Math Forum
    Replies: 5
    Last Post: September 24th 2010, 08:41 AM
  4. True or False. Prove if true show counter example if false.
    Posted in the Differential Geometry Forum
    Replies: 0
    Last Post: March 2nd 2010, 11:54 AM
  5. True or False hurting my head!! MK 2
    Posted in the Algebra Forum
    Replies: 2
    Last Post: June 6th 2009, 08:34 PM

Search Tags


/mathhelpforum @mathhelpforum