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6. Let R be a ring and let FR be a subring. Suppose that F is a field. (Wh ...
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6. Let R be a ring and let F?R be a subring. Suppose that F is a field. (When this happens, we say that R is an F-algebra.) Define scalar multiplication F×R?R by c?r:=cr (where the right-hand side denotes ring multiplication). Prove that this scalar multiplication and the usual ring addition turns R into a vector space over F.