设集合A={1,2,3,4,5,6},B={4,5,6,7},则满足A包含S且S∩B≠空集...
问题描述:
设集合A={1,2,3,4,5,6},B={4,5,6,7},则满足A包含S且S∩B≠空集...
设集合A={1,2,3,4,5,6},B={4,5,6,7},则满足A包含S且S∩B≠空集的集合S的个数是多少?怎么看出来的?
答
A的子集S个为2^6=64个,没有元素4,5,6的子集S的个数为:2^3=8个(只有元素1,2,3)
所以,满足A包含S且S∩B≠空集的集合S的个数是64-8=56个