Question

Let R be a ring, for all a in R, a^2 + a in Z(R). is R commutative?

Answer 1

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Answer 2

Z(R) is the central of the ring right?

Answer 3

central or center? I forgot. I think it is center.

Answer 4

yes, it is. Z(R) = {a in R : forall r in R, ar=ra}