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!

Can u gave me some examples of injective function.

  1. Feb 5, 2008 #1
    can u gave me some examples of injective function that is not surjective.
    Is f(x)=y a injective function that is not surjective?
  2. jcsd
  3. Feb 5, 2008 #2
    what about f:N--->N defined by f(n)=3n where n is from naturals, and N is the set of naturals.

    2-->6, so this function is injective since when f(n_1)=f(n_2)=>3n_1=3n_2=>n_1=n_2, but it is not surjective since there exists at least a numberf in the second N, in our case for example 1 that there are no numbers in N(the domain) such that when f(n)=1.
  4. Feb 5, 2008 #3
    You can go and define such functions as much as you wish, for i just made that example up. OR are you looking for any other example in particular?
  5. Feb 5, 2008 #4
    f:[0,1] -> R given by the identity function.

    f:R -> C given by identity function.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook