B1.7

Galois Theory
Part II, 2001

Prove that the Galois group GG of the polynomial X6+3X^{6}+3 over Q\mathbf{Q} is of order 6 . By explicitly describing the elements of GG, show that they have orders 1,2 or 3 . Hence deduce that GG is isomorphic to S3S_{3}.

Why does it follow that X6+3X^{6}+3 is reducible over the finite field Fp\mathbf{F}_{p}, for all primes p?p ?