证明1.Let A,B,and C be sets.Prove thatA∪包含 (A∪B ∪C).2.Let A,B,and C_英语解答

证明
1.Let A,B,and C be sets.Prove that
A∪包含 (A∪B ∪C).
2.Let A,B,and C be sets.Prove that
(A-C)∩(C -B) = 空集

人气：215 ℃　时间：2020-04-06 01:46:59

解答

1、Pick a∈A∪B ,then a a∈A or a∈B.there are two cases:case 1 :a∈A,then a must be a member ofone of A,B,C.that means a a∈A∪B ∪Ccase 2:a∈B,similarly discuss.so in both cases,a must be member of ...