Originally Posted by

**padsinseven** I don't know exactly what this means

The problem states

Z(sqrt-5)= ((a+b(sqrt-5) such that a,b are elements of Z) contained in C

What exactly does Z(sqrt-5) mean? I have never seen this before and I have to do a proof that looks similar.This is the proof I have to do if that sheds any light. Any tips on the notation or the proof would be appreciated.

Let S = {a + b sqrt(-5): a, b in Z}. Prove that

the number 6 in S has two fundamentally different factorizations

into primes of S. (Thus , unlike Z, the set S does not enjoy the property

of unique prime factorization.)