设集合P={1,2,3,4,5,6,7,8,9,10},P的子集A={a1,a2,a3},其中a1

问题描述:

设集合P={1,2,3,4,5,6,7,8,9,10},P的子集A={a1,a2,a3},其中a1

取a1 = 1,则a2至少为4,则a3 = 7a2 = 5,a3 = 8a2 = 6,a3 = 9a2 = 7,a3 = 10同样的取a1 = 2,则a2 = 5,a3 = 8a2 = 6,a3 = 9a2 = 7,a3 = 10取a1 = 3,a2 = 6,a3 = 9a2 = 7,a3 = 10取a1 = 4,a2 = 7,a3 = 10所以好子集的个...