环的性质 定理设<R,+,>是环,则 (1)Va∈R,a·0=0·=0 (2)Va,beR,(ab=a(b)=-ab 3)Va,bER,(ab)=ab (4)Va,b, cEr, a(b-c)=ab-ac, (b-c)a= ba-ca9 环的性质 定理 设<R,+,·>是环，则 (1) a∈R， a·0 = 0·a = 0 (2) a,b∈R， (−a)b = a(−b) = −ab (3) a,b∈R， (−a)(−b) = ab (4) a,b,c∈R，a(b−c) = ab−ac， (b−c)a = ba−ca