专题跟踪训练(七)集合、常用逻辑用语一、选择题1.(2018·河北衡水中学、河南郑州一中联考)已知全集U={1,2,3,4,5,6,7,8},A={3,4,5},B={1,3,6},则集合{2,7,8}是()A.A∪BB.A∩BC.∁U(A∩B)D.∁U(A∪B)[解析]解法一:由题意可知∁UA={1,2,6,7,8},∁UB={2,4,5,7,8},∴(∁UA)∩(∁UB)={2,7,8}.由集合的运算性质可知(∁UA)∩(∁UB)=∁U(A∪B),即∁U(A∪B)={2,7,8},故选D.解法二:画出韦恩图(如图所示),由图可知∁U(A∪B)={2,7,8}.故选D.[答案]D2.(2018·湖北七市联考)已知N是自然数集,设集合A=,B={0,1,2,3,4},则A∩B=()A.{0,2}B.{0,1,2}C.{2,3}D.{0,2,4}[解析] ∈N,∴x+1应为6的正约数,∴x+1=1或x+1=2或x+1=3或x+1=6,解得x=0或x=1或x=2或x=5,∴集合A={0,1,2,5},又B={0,1,2,3,4},∴A∩B={0,1,2}.故选B.[答案]B3.(2018·安徽安庆二模)已知集合A={1,3,a},B={1,a2-a+1},若B⊆A,则实数a=()A.-1B.2C.-1或2D.1或-1或2[解析]因为B⊆A,所以必有a2-a+1=3或a2-a+1=A.①若a2-a+1=3,则a2-a-2=0,解得a=-1或a=2
当a=-1时,A={1,3,-1},B={1,3},满足条件;当a=2时,A={1,3,2},B={1,3},满足条件.②若a2-a+1=a,则a2-2a+1=0,解得a=1,此时集合A={1,3,1},不满足集合中元素的互异性,所以a=1应舍去.综上,a=-1或2
故选C.[答案]C4.(2018·安徽皖南八校联考)已知集合A={(x