t Theorem 6.26: Let r be a commutative ring. Then for all a, bER, (a+b)=∑C(n)ab ◆ where n∈Z+ Theorem 6.26: Let R be a commutative ring. Then for all a,bR,  where nZ+ . = − + = n i n i n i a b C n i a b 0 ( ) ( , )