December 15th, 2007, 08:11 AM  #1 
Newbie Joined: Nov 2007 Posts: 7 Thanks: 0  Isomorphism
There is a well defined function (phi) : F > F given by the formula (phi)(a+b(sqrt)2) = ab(sqrt)2 Prove that phi is an isomorphism from F to F.

December 15th, 2007, 08:34 AM  #2  
Member Joined: Dec 2006 Posts: 39 Thanks: 0  Re: Isomorphism Quote:
You don't write what is F, you don't say what have you done with this problem, you don't mention why is phi well defined... This is not serious Regards Tonio  
December 15th, 2007, 02:51 PM  #3 
Newbie Joined: Nov 2007 Posts: 7 Thanks: 0 
your right, sorry F is all a+b(sqrt)2 with a and b rational and F is a subfield of R.

December 18th, 2007, 06:58 AM  #4 
Global Moderator Joined: Dec 2006 Posts: 20,805 Thanks: 2150 
What progress have you made so far?

December 18th, 2007, 07:57 AM  #5 
Newbie Joined: Nov 2007 Posts: 7 Thanks: 0 
not very much, i always have trouble starting


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