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October 29th, 2011, 10:23 AM  #1 
Newbie Joined: Oct 2011 Posts: 7 Thanks: 0  Onto and OneToOne Function
Why is the following function (f(n) = n + 17), onetoone, but not onto? The function should be able to take on values of (inf,inf) in the codomain or range, correct? 
October 29th, 2011, 12:45 PM  #2 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: Onto and OneToOne Function
I don't know. What's the domain? You'll get different answers depending on whether it's N > N or R > R or something else.

October 29th, 2011, 03:35 PM  #3 
Newbie Joined: Oct 2011 Posts: 7 Thanks: 0  Re: Onto and OneToOne Function
N > N

October 29th, 2011, 03:51 PM  #4 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: Onto and OneToOne Function
What value of n gives f(n) = 3?

October 29th, 2011, 04:22 PM  #5 
Newbie Joined: Oct 2011 Posts: 7 Thanks: 0  Re: Onto and OneToOne Function
for the given fcn. (14)... is that what you are asking? f(n) = n + 17; (14) + 17 > "3" 
October 29th, 2011, 04:25 PM  #6 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: Onto and OneToOne Function
But 14 isn't in N.


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