Prime ideal question (abstract algebra)

Metric_Space
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Homework Statement



Let D = Z[sqrt(10)], and let P be the ideal (2,sqrt(10)) 10). Prove that P is a prime
ideal of D.

Homework Equations



The Attempt at a Solution



Not sure where to start. I think elements are of the for a+b*sqrt(10), a,b integers.

Any hints as to what to do next?
 
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Hi Metric_Space! :smile:

So your ideal is \mathfrak{p}=(2,\sqrt{10})?

The first thing I would do is calculate \mathbb{Z}[\sqrt{10}]/\mathfrak{p} and check whether this is an integral domain...
 
Right..and there is a theorem that relates Z[10−−√]/p to prime ideals I think, right?
 
Metric_Space said:
Right..and there is a theorem that relates Z[10−−√]/p to prime ideals I think, right?

Uuh, maybe. But what I'm going for is that p is a prime ideal in a commutative ring R if and only if R/p is an integral domain...
 
cool..yes, I have a theorem like the one you mention -- that's a good start. Thanks for the hint.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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