(adsbygoogle = window.adsbygoogle || []).push({}); Let S be a ring such that for all s in S, s^{2}= s. Prove that S is commutative.

I've proved that for all s and t in S, (s + t)^{2}= s^{2}+ t^{2}, and also that s + s = 0. How would I go about proving that for all s and t, st = ts? Thanks. By the way, this isn't exactly homework, I was just practicing for the GREs.

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# Homework Help: Commutative Ring Problem

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