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Old Nov3-09, 02:24 AM                  #1
~Death~

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galios theory really stuck

E=Q(4th root of 2, i) and G is the galios group of E over Q

I found the minimal polynomial p(x) of 4th root of 2 over Q and Q(i) to be
x^4-2

I'm trying to show

(1) the galios group H of E over Q(i) is a normal subgroup of G

(2) If K is the galios group of Q(i) over Q show that it is isomorphic to G/H

so I can ultimately show that G is actually D4 (the group of symmetries)

but I'm compeltely stuck
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Old Nov3-09, 05:41 AM       Last edited by HallsofIvy; Nov4-09 at 04:52 AM..            #2
HallsofIvy

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Re: galios theory really stuck

Okay, what have you done so far? What are the roots of the polynomial LaTeX Code: x^4= 2 ? What is G? What is H?

By the way- it is 'Galois theory'. Capital G because it is a person's name and o before i.
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Old Nov3-09, 04:39 PM                  #3
~Death~

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Re: galios theory really stuck

Originally Posted by HallsofIvy View Post
Okay, what have you done so far? What are the roots of the polynomial LaTeX Code: x^4= 2 ? What is G? What is H?
I found the minimal polynomial of 4th root of 2 over Q and Q(i) to be
x^4-2

and the roots are +/-w, +/-wi where w is the 4th root of 2
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Old Nov3-09, 09:46 PM                  #4
Petek

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Re: galios theory really stuck

Additional hint: What is the splitting field of LaTeX Code: x^4 - 2 over Q?

Petek
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