REA book review question

Forum for the GRE subject test in mathematics.
dumplinghao123
Posts: 24
Joined: Sat Sep 22, 2012 4:34 pm

REA book review question

Postby dumplinghao123 » Thu Oct 04, 2012 11:07 pm

on Page 90, sample test 2, problem 62:
Let R be a ring and let x<>0 be a fixed element in R. Which of the followin is a subring of R?
In the choices, there is one {nx|n is an integer}.
I think this is a subring, since rings do not have to be closed under multiplication. However, the answer gives no.
Any idea?

vonLipwig
Posts: 51
Joined: Sat Mar 17, 2012 9:58 am

Re: REA book review question

Postby vonLipwig » Fri Oct 05, 2012 3:33 am

Some people require that a subring contain the multiplicative identity.

PNT
Posts: 37
Joined: Fri Mar 11, 2011 9:01 pm

Re: REA book review question

Postby PNT » Fri Oct 05, 2012 6:26 am

Rings do have to be closed under multiplication

dumplinghao123
Posts: 24
Joined: Sat Sep 22, 2012 4:34 pm

Re: REA book review question

Postby dumplinghao123 » Fri Oct 05, 2012 1:32 pm

oh yes... thanks for the reply. I got it now.




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