Contents
Student solutions for Assignment #3
Problem 50
Problem 73
Show that if $ p $ is a prime such that there is an integer $ b $ with $ p=b^2+4 $, then $ \mathbb{Z}[\sqrt{p}] $ is not a unique factorization domain.
- My solution only uses the fact that p is a sum of two squares (i.e. is congruent to 1 mod 4), so I'm not sure it's correct. -- Avi 20:05, 25 June 2013 (UTC)
Problem 94
Show f(x) = x4 + 5x2 + 3x + 2 is irreducible over the field of rational numbers.
Problem 101
(a) Show that x4 + x3 + x2 + x + 1 is irreducible in $ \mathbb{Z}_3[x] $.
(b) Show that x4 + 1 is not irreducible in $ \mathbb{Z}_3[x] $
Problem 107
Let R be a commutative ring with identity such that the identity map is the only ring automorphism of R. Prove that the set N of all nilpotent elements of R is an ideal of R
Problem 114
A local ring is a commutative ring with 1 that has a unique maximal ideal. Show that a ring R is local if and only if the set of non-units in R is an ideal.
