I'm going through a abstract algebra book I found and am trying to learn more about group theory by going through some of the proofs and practice sets, but am having trouble with the following:(adsbygoogle = window.adsbygoogle || []).push({});

Prove that G={a+b*sqrt(2) | a,b E R; a,b not both 0} is a group under ordinary multiplication.

Any help would be awesome!

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# Proving something is a group need help.

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