- #1
Andrusko
- 44
- 0
Homework Statement
In the ring [tex]Z[\sqrt{-3}][/tex] find all units and prove that 2 is irreducible but 7 is not.
Homework Equations
The Attempt at a Solution
Well a unit is a non-zero element of the ring that when multiplied by some other non-zero element of the ring gives the unity of the ring.
ie; [tex] ab = 1\;a,b \in Z[\sqrt{-3}] [/tex]
in otherwords b is the multiplicative inverse of a.
a is of the form [tex] a = x + y\sqrt{3} i [/tex] which just has the inverse of [tex]\frac{x - y\sqrt{3}i}{x^{2} + 3y^{2}}[/tex] (ie; b has this form)
So everything with the form of b with integer coefficients is a unit and 0 is not a unit.
I really don't understand what this question is asking, because I know what I've written down is completely stupid.
How would one go about finding the units of this ring?