Originally Posted by

**jmgilbert** Hi,

We have started with group theory this week and we have got a set of exercises... I have done the first 10 exercises, but after the 10th one they get so much harder and I have no clue how to solve this one. The next 10 exercises are based on this one...

I'd really appreciate if anyone could give me a hand. Thanks!

"Show that Z[(3)^(1/2)] has infintely many units. (Z is the integer set...)

Call a non-unit x in Z[(-1)^(1/2)] (Z[(-2)^(1/2)], Z[(-3)^(1/2)], Z[(3)^(1/2)] respectively) irreducible if

0 /= (not equal to) x /= y*z

for any two non-uunit y and z in Z[(-1)^(1/2)] (Z[(-2)^(1/2)], Z[(-3)^(1/2)], Z[(3)^(1/2)]

Note: I think Z[(-1)^(1/2)] would be the set of all complex numbers of the form a+b(-1)^(1/2). The elements of Z[(-1)^(1/2)] are called Gaussian integers... but I don't know if this has much to do with the actual question being asked :-/