Question

集合M={x|x=,k∈Z},N={x|x=,k∈Z},則(    )

A． M=N                    B. MN              　C.MN             D. M∩N=

Answer 1

C

解析:

對(duì)M將k分成兩類 k=2n或k=2n+1(n∈Z),

M={x|x=nπ+,n∈Z}∪{x|x=nπ+,n∈Z},

對(duì)N將k分成四類，k=4n或k=4n+1,k=4n+2,k=4n+3(n∈Z),

N={x|x=nπ+,n∈Z}∪{x|x=nπ+,n∈Z}∪{x|x=nπ+π,n∈Z}∪{x|x=nπ+,n∈Z}