can u gave me some examples of injective function.


by yaho8888
Tags: examples, function, gave, injective
yaho8888
yaho8888 is offline
#1
Feb5-08, 07:07 PM
P: 62
can u gave me some examples of injective function that is not surjective.
Is f(x)=y a injective function that is not surjective?
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sutupidmath
sutupidmath is offline
#2
Feb5-08, 09:43 PM
P: 1,635
what about f:N--->N defined by f(n)=3n where n is from naturals, and N is the set of naturals.

1-->3
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.
sutupidmath
sutupidmath is offline
#3
Feb5-08, 09:45 PM
P: 1,635
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?

andytoh
andytoh is offline
#4
Feb5-08, 10:37 PM
P: 363

can u gave me some examples of injective function.


f:[0,1] -> R given by the identity function.

f:R -> C given by identity function.


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