또 물어보기~ ^^

[갱갱이]

1) Show that 2 is equal to the product of a unit and the square of an irreducible element in Z[i].

2)Let A be a Euclidean domain with a Euclidean valuation υ.
if a,b∈A are associated,then prove that υ(a)=υ(b).

3)Prove that the function υ:Z → Z given by υ(n) = n^2 is a Euclidean valuation.