Set X has x Members and Set Y has y Members.Set Z consists of all members that are in either Set X or Set Y with the exc
问题描述：
Set X has x Members and Set Y has y Members.Set Z consists of all members that are in either Set X or Set Y with the exception of the k common members(k larger than 0).which of the following represents the members of members in Set
为什么答案是X+Y-2K
答
X有x人,Y有y人,Z由所有只单在X,或Y得人,即,除了K个都参加得人组成,Z得人数如何表示?
X+Y得结果是X得人+Y得人,其中,X个人中包含K,y个人中同样包含K,所以要减2K,楼主明白否?
：}