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Homework Help: How can I prove it? (injection, bijection, surjection)

  1. Sep 15, 2011 #1
    1. The problem statement, all variables and given/known data
    How can I prove this?

    If g°f is a bijective function, then g is surjective and f is injective.
    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Sep 15, 2011 #2
    First what does g°f mean
    what does bijective mean
    what does surjective mean
    what does injective mean
  4. Sep 15, 2011 #3
    Start of with let g of f be a bijection, than state of the definition of a bijection. From there you can prove what must be true of g and f for g of f to meet the definition.
  5. Sep 16, 2011 #4
    I can see why it is need to be true, when I draw it, unfotunately I cannot write down the solution in a mathematical way.
  6. Sep 16, 2011 #5
    To start say
    Let g°f be a bijective function.

    then what can you say about g°f
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