在og上我遇到一个题,急求您的帮助:Set X has x member 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>0). Which of the following represents the number of member in set Z ? 9 z- b) L }* ~' A2 R" g, o% C8 [3 C2 }* z. `4 ^- |* p
A x+y+k3 K% q6 U2 N7 }4 A. @
B x+y-k 8 B% M: S# B8 }; T0 G: s( j+ U' qC x+y+2k 6 Y6 N3 u- o T! ?4 a9 P( B; qD x+y-2k% S P, M) T6 C: t
E 2x+2y-2k + \9 d2 }( J5 H4 g为什么答案是E? 请大家指点。# Q' D Q* e/ o( }# y7 I( }
另外拜托能不能再把题目中高亮的部分办我翻译一下,我还是理解得不大懂。" ^: B! A4 Z3 r- A0 F
最后想问一下大家,og的数学答案讲解应该在什么地方找到? 在新东方门口买到的真题下册的答案讲解又应该如何获取?