Take a galois group $Gal(K/\mathbb{Q})$ isomorphic to $C_{16}$. How many subfields $L$ exist such that $[K:L] = 4$?

48 Views Asked by At

Take a galois group $Gal(K/\mathbb{Q})$ isomorphic to $C_{16}$. How many subfields $L$ exist such that $[K:L] = 4$?

I am inclined to say 4 but I cannot prove it.

2

There are 2 best solutions below

0
On

Hint

This is exactly Galois theorem : you have a one to one correspondance between the sub-fields of degree 4 of $L$ and the subgroups of $C_{16}$ with 4 elements.

0
On

By the Galois correspondence, only one. For $C_{16}$ has a unique subgroup of order $4$.