I am also having trouble proving this statement: Let R be a commutative ring which is not a domain. Then R has no units other that 1 and -1. Is this true or is Zp a counterexample.
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Originally Posted by chadlyter Then R has no units other that 1 and -1. False. Consider Z_m where m is not a prime and m>1. This is not an integral domain. However the units are the numbers relatively prime to m. Is this true or is Zp a counterexample. No. Z_p is an integral domain. How can it be a counterexample?
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