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

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}