第2课时　集合的表示

课后篇巩固提升

A组　基础巩固

1.已知集合A={x|x(x+4)=0},则下列结论正确的是0(　　)

A.0∈A B.-4∉A

C.4∈A D.0∉A

解析:∵A={x|x(x+4)=0}={0,-4},∴0∈A.

答案:A

2.设集合M={a2-a,0},若a∈M,则实数a的值为(　　)

A.0 B.2 C.2或0 D.2或-2

解析:因为集合M={a2-a,0},a∈M,所以a=a2-a或a=0(舍去),所以a=2.故选B.

答案:B

3.已知集合A={-2,2},B={m|m=x+y,x∈A,y∈A},则集合B等于(　　)

A.{-4,4} B.{-4,0,4} C.{-4,0} D.{0}

解析:∵集合A={-2,2},B={m|m=x+y,x∈A,y∈A},∴集合B={-4,0,4},故选B.

答案:B

4.集合{3"," 5/2 "," 7/3 "," 9/4 ",..." }用描述法可表示为(　　)

A.{x├|x=(2n+1)/2^n "," n"∈" N^" " ┤}

B.{x├|x=(2n+3)/n "," n"∈" N^" " ┤}

C.{x├|x=(2n"-" 1)/n "," n"∈" N^" " ┤}

D.{x├|x=(2n+1)/n "," n"∈" N^" " ┤}