Results 1 to 2 of 2

Math Help - Really easy proof just don't know where to start

  1. #1
    Junior Member
    Joined
    Aug 2006
    Posts
    34

    Really easy proof just don't know where to start

    I got a really easy proof that i know are true but i'm really bad about proving things just need a little help getting started

    suppose f:A->B and g:B->C show that g0f is a constant function if either f or g is constant

    it is really easy to see that this is true by def but not sure how to formally prove this
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    10
    Quote Originally Posted by action259 View Post
    I got a really easy proof that i know are true but i'm really bad about proving things just need a little help getting started

    suppose f:A->B and g:B->C show that g0f is a constant function if either f or g is constant

    it is really easy to see that this is true by def but not sure how to formally prove this
    We are mapping two non-empty sets by,
    f:A\to B such that,
    f(x)=b\in B \, \forall x\in A
    Let,
    g:B\to C be any function between two non-empty sets B and C,
    Then,
    g \circ f:A\to C
    Is a map between these two sets.
    It is,
    g(f(x))=g(b)\forall x\in A
    Thus, it is konstant.

    Similary argument in the other direction.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Help with this proof. Not exactly sure where to start.
    Posted in the Discrete Math Forum
    Replies: 7
    Last Post: October 5th 2010, 07:37 PM
  2. existence proof, how to start?
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 12th 2010, 10:34 PM
  3. Need help on an easy proof for everyone
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: March 7th 2010, 04:11 AM
  4. Replies: 4
    Last Post: November 24th 2009, 04:38 PM
  5. Probably an easy gcd proof
    Posted in the Number Theory Forum
    Replies: 4
    Last Post: April 5th 2007, 07:51 PM

Search Tags


/mathhelpforum @mathhelpforum