[monjaro]

Could you suggest any resource for understanding this theorem? I have a math degree, but I never came across any Galois theory.

[betterunix]

Most people like the Dummit & Foote book; it tends to be loaded with examples rather than a lot of dense symbolic arguments:

http://www.amazon.com/Abstract-Algebra-Edition-David-Dummit/...

When I learned it, though, it was from this Dover book, which is more affordable:

http://www.amazon.com/Elements-Abstract-Algebra-Dover-Mathem...