1.3 集合的基本运算常考题型训练(含详解答案)
1.3集合的基本运算常考题型训练
题型:求集合的交集
1、简单求交集
1.集合A ={1,3},B ={2,3,4}则A∩B =( )
A .{1}
B .{2}
C .{3}
D .{1,2,3,4}
2.已知集合{|||2}A x x =<,{1,0,1,2,3}B =-,则A B =
A .{0,1}
B .{0,1,2}
C .{1,0,1}-
D .{1,0,1,2}-
3.已知集合{}{}02,1,0,1,2M x x N =≤<=-,则M
N =__________. 4.已知集合{}0,1,2,3,4,5A =,{}1,3,5,7,9B =则A B =( )
A .{}1,2,3,5
B .{}0,1,3,5
C .{}1,3,5
D .{}0,1,2,3,4,5,7,9
5.已知集合A ={1,2,3,4},B ={1,3,5},则A∩B=
A .{1,2,3,4,5}
B .{1,3,5}
C .{1,4}
D .{1,3}
6.设集合{}2,3,4,5M =,集合{}2,4,6N =,则M N ?是( )
A .{}2,3,4,5
B .{}2,4
C .{}2,3,4,5,6
D .{}2,4,6
7.已知集合{}1,2,3,4A =,{}1,4,5B =,C A
B =,则
C 的子集共有( ) A .2个 B .3个 C .8个
D .4个 8.已知集合A={1,2,3,4},B={2,4,6,8},则A B 中元素的个数为
A .1
B .2
C .3
D .4
9.已知集合M={x|-3 A .{-2,-1,0,1} B .{-3,-2,-1,0} C .{-2,-1,0} D .{-3,-2,-1 } 10.已知集合{}{}22,1,0,2,3,|1,A B y y x x A =--==-∈,则A B 中元素的个数是 A .2 B .3 C .4 D .5 11.若集合{|210}A x x =->,{|||1}B x x =<,则A B = . 12.集合{|03}A x x =<<,{|||2}B x x =<,则A B =__________ 13.已知集合{|02}A x x =<<,{|1}B x x =>,则A B =______ 14.已知集合A ={x |x -2<1},B ={x |2x +1>3},则A ∩B =( ) A .{x |0<x <1} B .{x |2<x <3} C .{x |1<x <3} D .? 15.已知集合={|1}A x x >-,{|2}B x x =<,则A ∩B = A .(–1,+∞) B .(–∞,2) C .(–1,2) D .? 16.已知集合{}1,2,3,4,{|32},A B y y x x A ===-∈,则A B ?=( ) A .{1} B .{4} C .{1,3} D .{1,4} 17.已知集合{12}A x x =-≤≤,{13}B x x =≤≤,则A B =( ) A .[1,2] B .[1,2]- C .[1,3]- D .[1,3] 18.若集合{|23}A x x =-≤≤,{1B x x =<-或}4x >,则集合A B 等于( ) A .{|3x x ≤或}4x > B .{}|13x x -<≤ C .{}|21x x --<≤ D .21(1)1-=-+-m y m x x 19.已知集合(){}22,1A x y x y =+=,(){},B x y y x ==,则集合A B 的子集的个数为( ) A .2 B .4 C .8 D .16 20.若集合{|23}A x x =-≤≤,{|14}B x x x =<->或,则集合A B 等于( ) A .{}|34x x x >或≤ B .{}|13x x -<≤ C .{}|21x x --<≤ D .21(1)1m y m x x -=-+- 2、求参数 1.已知集合{3,4,5,6}A =,{}B a =,若{6}A B =,则a =( ) A .3 B .4 C .5 D .6 2.已知集合{A x y ==,{}B x x a =≥,若A B A =,则实数a 的取值范围是( ) A .(],3-∞- B .(),3-∞- C .(],0-∞ D .[)3,+∞ 3.设集合{}1,2,4A =,{}240B x x x m =-+=.若{}1A B ?=,则B = ( ) A .{}1,3- B .{}1,0 C .{}1,3 D .{}1,5 4.已知[1,)A =+∞,[0,31]B a =-,若A B ?≠?,则实数a 的取值范围是( ) A .[1,)+∞ B .1,12?????? C .2,3?? +∞???? D .(1,)+∞ 5.集合{|12}A x x =-,{|}B x x a =<. (1)若A B A =,求实数a 的取值范围;(2)若A B =?,求实数a 的取值范围. 6.已知集合A ={x|2a +1≤x≤3a -5},B ={x|x <-1,或x >16},分别根据下列条件求实数a 的取值范围. (1)A∩B =?;(2)A?(A∩B ). 7.设集合{}240A x x x =+=,(){} 222110B x x a x a =+++-=, (1)当1a =-时,求A B ;(2)若A B B =,求a 的取值范围. 8.已知集合{}13A x x =<<,集合{}21B x m x m =<<- (1)若A B ?,求实数m 的取值范围. (2)若A B =?,求实数m 的取值范围. 9.设集合{}1,0,3A =-,{}3,21B a a =++,{}3A B ?=,则实数a 的值为________, 10.已知集合{}1,2A =,{} 2,3B a a =+,若A B={1}?则实数a 的值为________ 题型:求集合的并集 1、简单求解 1.已知集合{0,1}A =,{0,1,2,3}B =,则A B 中的元素个数为________. 2、求参数 1.设集合{}{} 23,0,3,1A B t t =-=-+,若A B A ?=,则t 的值为( ) A .1- B .2 C .1 D .2或1- 3.已知集合{A =,{}1,B m =,若A B A ?=,则m =( ) A .0 B .0或3 C .1 D .1或3 4.已知{}{}2512A x x B x m x m =-≤≤=+≤≤,,若A B A ?=,求实数m 的取值范围. 5.已知集合{|12}A x x =≤≤,集合{|}B x x a =≥,若A B B ?=,则实数a 的取值范围是_______. 题型:求集合的补集 1、简单求补集 1.设集合{}{}1,3,5,7,9,11,5,9==A B ,则 A B =( ) A .{}5,9 B .{}1,3,7,11 C .{}1,3,7,9,11 D .{}1,3,5,7,9,11 2.已知集合U ={-2,-1,0,1,2},A ={0,1,2},则?U A =( ) A .{}2,1,0-- B .{}2,1-- C .{0,1,2} D .{}1,2 3.设集合A ={0,2,4,6,8,10},B ={4,8},则?A B = A .{4,8} B .{0,2,6} C .{0,2,6,10} D .{0,2,4,6,8,10} 4.设全集U =R ,集合{|3A x x =>或1}x <,则U A __. 5.已知全集U =R ,集合{|2A x x =<-或2}x >,则U A ( ) A .(2,2)- B .(,2)(2,)-∞-+∞ C .[2,2]- D .(,2][24,)-∞-+∞ 2、求参数 1.设全集{}25,3,4U a a =+-,U 的子集{|2|,5}A a =+.如果{3}U A =,求实数a 的值. 2.设集合{}0,1,2,3U =,集合{} 2|0A x U x mx =∈+=,若{}1,2U C A =,则实数m =_____. 3.设全集{}22,3,3U a a =+-,集合{} ,3A a =,{}2U C A =,则a =___________. 题型:集合的综合运算 1、简单的计算 1.已知全集{}1,0,1,2,3U =-,集合{}0,1,2A =,{}1,0,1B =-,则()U A B ?=( ) A .{}1- B .{}0,1 C .{}1,2,3- D .{}1,0,1,3- 2.已知全集U ={1,2,3,4,5,6},集合A ={2,3,5},集合B ={1,3,4,6},则集合A ∩(?U B )=( ) A .{3} B .{2,5} C .{1,4,6} D .{2,3,5} 3.已知全集{}1,2,3,4,5,6,7,8U =,集合{}2,3,5,6A =,集合{}1,3,4,6,7B =,则集合U A B ?=( ) A .{}2,5 B .{}3,6 C .{}2,5,6 D .{}2,3,5,6,8 4.已知全集{1,3,5,7}U =,集合{1,3}A =,{3,5}B =,则 ()()U U A B ?=( ) A .{3} B .{7} C .{3,7} D .{1,3,5} 5.设全集,集合{}1,4M =,{}1,3,5N =,则()U N M =( ) A .{}1 B .{}3,5 C .{}1,3,4,5 D .{}1,2,3,5,6 6.已知全集{0,1,2,3,4,5},集合{1,5}A =,集合{}2B =,则集合() U C A B =( ) A .{}0,2,3,4 B .{}0,3,4 C .{}2 D .? 7.设集合{}1,2,3,4,5U =,{}13,5A =,,{}2,3,5B =,则 ()U C A B 等于( ) A .{}1,2,4 B .{}4 C .{}3,5 D .? 8.已知全集{1,2,3,4,5,6}U =,集合{1,3,4}A =,集合{1,3,5}B ,则() U C A B ( ) A .{5} B .{1,3} C .{1,3,4,5} D .? 9.已知集合,A B 均为全集{1,2,3,4,5,6,7}U =的子集,集合{1,2,3,4}A =,则满足{1,2}U A B =的集合B 可以是( ) A .{1,2,3,4} B .{1,2,7} C .{3,4,5,6} D .{1,2,3} 10.已知全集{1,2,3,4,5,6},U 集合{1,3,4}A =,集合{1,3,5}B ,则()U C A B ( ) A .{5} B .{1,3} C .{1,3,4,5} D .? 11.已知全集{}1,2,3,4,5,6,7,8,9U =,{}2A B ?=,() (){1,9}U U C A C B =,(){4,6,8}U C A B =,则集合A =________. 12.已知集合{}|6A x x =>,{}2,5,6,8,10B =,则() R C A B =( ) A .{}8,10 B .{}2,5 C .{}6,8,10 D .{}2,5,6 13.设集合{}1,1,2,3,5A =-,{}2,3,4B = ,{|13}C x R x =∈< ,则()A C B = A .{2} B .{2,3} C .{-1,2,3} D .{1,2,3,4} 14.设全集为R ,集合A ={x |x 2?4<0},B ={x |?1 A .(?2,?0) B .(?2,?1) C .(?2,?1] D .(?2,?2) 15.已知集合{0,1,2},{1235}A B x x ==<+<∣,则()R A B =( ) A .{0,1} B .{0,2} C .{1,2} D .? 16.设全集U =R ,集合{|1}A x x =≥,{|03}B x x =≤<,则集合 ()U A B 是( ) A .{|01}x x << B .{|01}x x ≤< C .{|01}x x <≤ D .{|01}x x ≤≤ 17.已知全集,{|1},{|2}U R M x x P x x ==≤=,则 ()U M P ?=( ) A .{|12}x x << B .{|1}x x C .{|2}x x ≤ D .{|1x x 或2}x 18.设集合{}1,0,1A =-,{}1,2,3B =-,{}11C x R x =∈-≤<,则()A B C =( ) A .{}1- B .{}1,0- C .{}1,1- D .{}1,0,1- 19.已知集合{}{}||12A x x a B x x =<=<<,,且()A B ?=R R ,则实数a 的取值范围是( ) A .1a ≤ B .1a < C .2a ≥ D .2a > 20.已知全集={1,2345}={12}={234}U A B , ,,,,,,,,则()U A B =( ) A .{}2,3 B .{}3,4 C .{}3 D .{}4 21.已知集合{}|35M x N x *=∈-<≤,{|5N x x =≤-或}5x ≥,则()R M N =( ) A .{}1,2,3,4,5 B .{} 35x x -<< C .{}5|5x x -<≤ D .{}1,2,3,4 22.已知集合{}A x x a =<,{}2B x x =<,且()R A B =R ,则a 满足( ) A .2a ≥ B .2a > C .2a < D .2a ≤ 23.设U ={1,2,3,4,5},且A ∩B ={2},()U C A B ?={4},() ()U U C A C B ={1,5},则下列结论正确的 是( ) A .3∈A ,3∈B B .2∈U C A ,3∈B C .3∈U C B ,3∈A D .3∈U C A ,3∈U C B 24.设全集U ={|20x x 的素数}, (){3,5}U B A ?=,(){7,19}U A B ?=,()(){2,17}U U A B ?=,求集合A ,B . 25.已知集合{|21}A x x =-<<,{}2|20B x x x =+=.全集U =R ,求 ()()U U A B ?和()U A B ?. 2、求参数 1.已知集合{}2|0A x x ax b =++=,{} 2|150B x x cx =++=.若{3}A B ?=,{3,5}A B ?=,求a ,b 的值. 2.已知集合{}2|2A x x -=≤≤,集合{}|1B x x =>. (1)求()R C B A ?;(2)设集合{}|6M x a x a =<<+,且A M M ?=,求实数a 的取值范围. 3.设全集为R ,集合{|36}A x x =≤<,{|29}B x x =<<. (1)分别求A B ?,()R C B A ?; (2)已知{|1}C x a x a =<<+,若C B ?,求实数a 的取值范围构成的集合. 4.已知全集U =R ,集合{}|7217A x x =-≤-≤,{}|132B x m x m =-≤≤-, ,1)当3m =时,求A B 与()U A B ?,,2)若A B B =,求实数m 的取值范围. 5.已知集合{|3A x x =≤-或2}x ≥,{|15}B x x =<<,{|12}C x m x m =-≤≤ (1)求A B ,()R C A B ?; (2)若B C C ?=,求实数m 的取值范围. 6.已知集合{,,}A a b c =. (1)写出所有满足条件A B A ?=的集合B ; (2)满足条件A C C =的集合C 有多少个? 7.已知集合2{2342}A a a =++, ,,2{07242}B a a a =-+-,,,,{}3,7A B ?=.求a 的值及集合A B 。 8.设全集为R ,{}|37A x x =≤<,{}|210B x x =<<.(1)求A B ;(2)求()R A B ?. 9.已知集合{|121}A x a x a =-<<+,{}B 03x x =<≤,U =R . (1)若12 a =,求A B ?;()U A C B ?.(2)若A B φ?=,求实数a 的取值范围. 10.已知集合A ={x |1<x <6},B ={x |2<x <10},C ={x |5-a <x <a }. (1)求A ∪B ,(?R A )∩B ;(2)若C ?B ,求实数a 的取值范围. 11.设全集U =R ,集合{}13A x x =-≤<,{}242B x x x =-≥-. (1)求()U A B ;(2)若集合{}0C x x a =->,满足C C =B ∪,求实数a 的取值范围. 12.已知集合{|02}A x x =≤≤,{|3}B x a x a =≤≤+. (1)若()R U A B ?≠,求a 的取值范围;(2)若A B A ≠,求a 的取值范围. 13.已知集合{}|03A x x =<<,{}|8B x a x a =<<+ (1)若A B B ?=,求实数a 的取值范围;(2)若A B =?,求实数a 的取值范围. 14.已知,[1,3],{|3}U R A B x a x a ===≤≤+ (1)若2a =时,求,,()U B A B C A B ?.(2)若()U C A B R ?=,求a 的范围. 15.已知集合[][]1,3,,6,A B m m m R =-=+∈. (1)当2m =时,求R A B ;(2)若A B A =,求实数m 的取值范围. 16.设全集U =R ,集合{}14A x x =≤<,{} 23B x a x a =≤<-. (1)若2a =-,求B A ?,U B C A ?;(2)若A B A =,求实数a 的取值范围. 17.已知集合{}|{|023}A x x B x a x a ≤≤≤≤=,=+ . (1)若()R A B R =,求a 的取值范围;(2)是否存在a 使()R A B R =且A B ?=∩? 18.已知集合U =R ,{|12}A x x =-≤<,{|03}B x x =<<,{|13}C x m x m =<≤-. (1)求A B ,A B ,()()U U A B ?;(2)若()C A C ?,求m 的取值集合. 19.已知全集为R ,函数()()lg 1f x x =-的定义域为集合A ,集合(){}|16B x x x =->. (1)求A B ;(2)若{}|11C x m x m =-<<+,()() R C A B ?,求实数m 的取值范围. 20.已知全集{}|0U x x =>,集合{}{}{}|37|210|5A x x B x x C x a x a =≤==-<,<< ,<<. (1)求()U A B C A B ??,;(2)若()C A B ??, 求a 的取值范围. 21.设集合{|14},{|14},{|}A x x x B x x C x x a ==≤≤=<或 (1)求,A B A B ;(2)若A C C =,求a 的取值范围. 22集合{|2 1 A x x =-<<或1}x >,而{|2}A B x x =>-∪,{|13}A B x x =<≤∩,则集合B =________. 题型:Venn 图求解 1.记全集{1,2,3,4,5,6,7,8},U =集合{1,2,3,5},{2,4,6},A=B =则图中阴影部分所表示的集合是 ( ) A .{4,6,7,8} B .{2} C .{7,8} D .{1,2,3,4,5,6} 2.如果全集U =R ,{}1,2,3,4A =,{}3,4,5B =,则图中的阴影部分表示的集合是( ) A .{}1,2,3,4,5 B .{}3,4 C .{}1,2,3,4 D .{}1,2,5 3.若集合{}1,2,3,4,5A =,集合{} 04B x x =<<,则图中阴影部分表示( ) A .{}1234,,, B .{}123,, C .{}4,5 D .{}1,4 4.已知全集U =R ,集合A ={0,1,2,3,4},{20}B x x x =><或,则图中阴影部分表示的集合为( , A .{0,1,2} B .{1,2} C .{3,4} D .{0,3,4} 5.下列表示图形中的阴影部分的是( ) A .()()A C B C B .()()A B A C C .()()A B B C D .()A B C 6.已知全集U =R ,则下列能正确表示集合{0,1,2}M =和2{|20}N x x x =+=关系的韦恩(Venn )图 是 A . B . C . D . 7.已知全集{1,3,5,7}U =,集合{1,3}A =,{3,5}B =,则如图所示阴影区域表示的集合为( ) A .{3} B .{7} C .{3,7} D .{1,3,5} 8.已知全集U =R ,集合{0,1,2,3,4,5}A =,{|2}B x x =≥,则图中阴影部分所表示的集合为( ) A .{}1 B .{}0,1 C .{}1,2 D .{}0,1,2 9.已知全集U R =,集合{|08,}A x x x R =<<∈和{|35,}B x x x Z =-<<∈关系的韦恩图如图所示,则阴影部分所表示集合中的元素共有( ) A .3个 B .4个 C .5个 D .无数个 10.设全集{}U 1,2,3,4,5=,集合{}1,3,5M =,{}2,5N =,则Venn 图中阴影部分表示的集合是( ) A .{}5 B .{}1,3 C .{}2,4 D .{}2,3,4 1.3集合的基本运算解析 题型:求集合的交集 1、简单求交集 1.集合A ={1,3},B ={2,3,4}则A∩B =( ) A .{1} B .{2} C .{3} D .{1,2,3,4} 【解析】根据集合交集的运算可知, ,故选C . 2.已知集合{|||2}A x x =<,{1,0,1,2,3}B =-,则A B = A .{0,1} B .{0,1,2} C .{1,0,1}- D .{1,0,1,2}- 【解析】由,得,选C. 3.已知集合{}{}02,1,0,1,2M x x N =≤<=-,则M N =__________. 【解析】因为{}{}02,1,0,1,2M x x N =≤<=-,所以{}0,1M N ?=. 4.已知集合{}0,1,2,3,4,5A =,{}1,3,5,7,9B =则A B =( ) A .{}1,2,3,5 B .{}0,1,3,5 C .{}1,3,5 D .{}0,1,2,3,4,5,7,9 【解析】因为集合{}0,1,2,3,4,5A =,{}1,3,5,7,9B =,故{}1,3,5A B =.故选:C 5.已知集合A ={1,2,3,4},B ={1,3,5},则A∩B= A .{1,2,3,4,5} B .{1,3,5} C .{1,4} D .{1,3} 【解析】因为集合1234135A B ={,,,},={,,},所以13A B ?={,} ,故选D . 6.设集合{}2,3,4,5M =,集合{}2,4,6N =,则M N ?是( ) A .{}2,3,4,5 B .{}2,4 C .{}2,3,4,5,6 D .{}2,4,6 【解析】{}{}2,3,4,5,2,4,6M N ==,{}2,4M N ∴?=,故选:B 7.已知集合{}1,2,3,4A =,{}1,4,5B =,C A B =,则C 的子集共有( ) A .2个 B .3个 C .8个 D .4个 【解析】{1,4}C A B ==,C 的子集有{}1,{}4,{}1,4,?,共4个.故选:D 8.已知集合A={1,2,3,4},B={2,4,6,8},则A B 中元素的个数为 A .1 B .2 C .3 D .4 【解析】由题意可得{}2,4A B =,故A B 中元素的个数为2,所以选B. 9.已知集合M={x|-3 A .{-2,-1,0,1} B .{-3,-2,-1,0} C .{-2,-1,0} D .{-3,-2,-1 } 【解析】因为集合M=,所以M∩N={0,-1,-2},故选C. 10.已知集合{}{}22,1,0,2,3,|1,A B y y x x A =--==-∈,则A B 中元素的个数是 A .2 B .3 C .4 D .5 【解析】当2x =±时,3y =;当1x =-时,0y =;当0x =时,1y =-;当3x =时,8y =,所以{}1,0,3,8B =-,所以{}1,0,3A B ?=-,故选B. 11.若集合{|210}A x x =->,{|||1}B x x =<,则A B = . 【解析】1,2A ??=+∞ ??? ,(1,1)B =-,A∩B=1,12?? ???. 12.集合{|03}A x x =<<,{|||2}B x x =<,则A B =__________ 【解析】由题意{|||2}{|22}B x x x x =<=-<<, 则A B ={|22{|}(003}{|02})2,x x x x x x -<<=<<<<=. 故答案为:(0,2). 13.已知集合{|02}A x x =<<,{|1}B x x =>,则A B =______ 【解析】因为集合{|02}A x x =<<,{|1}B x x =>,所以{|12}A B x x =<<. 故答案为:{|12}x x << 14.已知集合A ={x |x -2<1},B ={x |2x +1>3},则A ∩B =( ) A .{x |0<x <1} B .{x |2<x <3} C .{x |1<x <3} D .? 【解析】解:因为{}|21A x x =-<,所以{}|3A x x =<;因为{}|213B x x =+>,所以{}|1B x x => 所以{}|13A B x x =<< 故选:C 15.已知集合={|1}A x x >-,{|2}B x x =<,则A ∩B = A .(–1,+∞) B .(–∞,2) C .(–1,2) D .? 【解析】由题知,(1,2)A B =-,故选C . 16.已知集合{}1,2,3,4,{|32},A B y y x x A ===-∈,则A B ?=( ) A .{1} B .{4} C .{1,3} D .{1,4} 【解析】因为集合B 中,x ∈A ,所以当x =1时,y =3-2=1; 当x =2时,y =3×2-2=4; 当x =3时,y =3×3-2=7; 当x =4时,y =3×4-2=10. 即B ={1,4,7,10}. 又因为A ={1,2,3,4},所以A ∩B ={1,4}.故选D. 17.已知集合{12}A x x =-≤≤,{13}B x x =≤≤,则A B =( ) A .[1,2] B .[1,2]- C .[1,3]- D .[1,3] 【解析】依题意A B =[1,2].故选:A 18.若集合{|23}A x x =-≤≤,{1B x x =<-或}4x >,则集合A B 等于( ) A .{|3x x ≤或}4x > B .{}|13x x -<≤ C .{}|21x x --<≤ D .21(1)1-=-+-m y m x x 【解析】{|23}A B x x ?=-≤≤?{1x x <-或}4x >{}|21x x =-≤<-. 故选:C . 19.已知集合(){}22,1A x y x y =+=,(){},B x y y x ==,则集合A B 的子集的个数为( ) A .2 B .4 C .8 D .16 【解析】解221x y y x ?+=??=?? 得,22x y ?=-????=?? 或22x y ? =????=?? ; ∴,2222A B ?????=- ?? ????????,即A B 中有2个元素;A B ∴子集个数为4.故选:B . 20.若集合{|23}A x x =-≤≤,{|14}B x x x =<->或,则集合A B 等于( ) A .{}|34x x x >或≤ B .{}|13x x -<≤ C .{}|21x x --<≤ D .21(1)1m y m x x -=-+- 【解析】{}{|23}{|14}|21A B x x x x x x x 或?=-≤≤?-=-≤<-,选C. 2、求参数 1.已知集合{3,4,5,6}A =,{}B a =,若{6}A B =,则a =( ) A .3 B .4 C .5 D .6 【解析】由{6}A B =可知6a =,故选D. 2. 已知集合{A x y ==,{}B x x a =≥,若A B A =,则实数a 的取值范围是( ) A .(],3-∞- B .(),3-∞- C .(],0-∞ D .[ )3,+∞ 【解析】由已知得[]3,3A =-,由A B A =,则A B ?,又[),B a =+∞,所以3a ≤-.故选A. 3.设集合{}1,2,4A =,{} 240B x x x m =-+=.若{}1A B ?=,则B = ( ) A .{}1,3- B .{}1,0 C .{}1,3 D .{}1,5 【解析】∵ 集合{}124A ,,=,{} 2|40B x x x m =-+=,{}1A B ?= ∴1x =是方程240x x m -+=的解,即140m -+= ∴3m = ∴{}{} {}22|40|43013B x x x m x x x =-+==-+==,,故选C 4.已知[1,)A =+∞,[0,31]B a =-,若A B ?≠?,则实数a 的取值范围是( ) A .[1,)+∞ B .1,12?????? C .2,3??+∞???? D .(1,)+∞ 【解析】由题意可得:311a -≥,求解不等式有:23a ≥ ,即实数a 的取值范围是2,3??+∞????. 故选C . 5.集合{|12}A x x =-,{|}B x x a =<. (1)若A B A =,求实数a 的取值范围;(2)若A B =?,求实数a 的取值范围. 【解析】解:(1)由集合{|12}A x x =-,{|}B x x a =<, 因为A B A =,所以A B ?,则2a >,即实数a 的取值范围为2a >; (2)因为 A B =?,又B ≠?,可得1a -,故实数a 的取值范围为1a -. 6.已知集合A ={x|2a +1≤x≤3a -5},B ={x|x <-1,或x >16},分别根据下列条件求实数a 的取值范围. (1)A∩B =?;(2)A?(A∩B ). 【解析】(1)若A =,,则A∩B =,成立.此时2a +1>3a -5,即a <6. 若A≠,,则2135 {2113516 a a a a +≤-+≥--≤解得6≤a≤7. 综上,满足条件A∩B =,的实数a 的取值范围是{a|a≤7}. (2)因为A,(A∩B ),且(A∩B ),A ,所以A∩B =A ,即A,B . 显然A =,满足条件,此时a <6. 若A≠,,则2135{351a a a +≤--<-或2135{2116 a a a +≤-+> 由2135{351a a a +≤--<-解得a,,;由2135{2116a a a +≤-+>解得a >152 . 综上,满足条件A,(A∩B )的实数a 的取值范围是{a|a <6或a >152 }. 7.设集合{}240A x x x =+=,(){} 222110B x x a x a =+++-=, (1)当1a =-时,求A B ;(2)若A B B =,求a 的取值范围. 【解析】(1)1a =-时,集合{} {}2240={0,4},{|0}0A x x x B x x =+=-=== {}0A B ∴= (2)根据题意:{} 240={0,4},A x x x =+=- A B B =即:B A ?,且集合B 为方程()222110x a x a +++-=的解集, 分四种情况讨论: (i )22,[2(1)]4(1)8801B a a a a =??=+--=+<∴<-,满足题意; (ii )22 {0},[2(1)]4(1)880,B a a a =?=+--=+=且210a -=,1a ∴=-; (iii )22{4},[2(1)]4(1)880,B a a a =-?=+--=+=且2168(1)10a a -++-=,无解; (iv ) 2{04},10,B a =--=, 且2168(1)10a a -++-=,1a 综上:1a =或1a ≤-. 8.已知集合{}13A x x =<<,集合{}21B x m x m =<<- (1)若A B ?,求实数m 的取值范围. (2)若A B =?,求实数m 的取值范围. 【解析】(1)因为{}13A x x =<<,所以A ≠?,又因为A B ?,所以有:1231212m m m m m ->??≤-?≤-??≥? ; (2)因为A B =?,所以有以下二种情形: 当B =?时,显然A B =?成立,此时1213m m m ≥-?≥; 当B ≠?时,要想A B =?成立,只需:1232m m m ->??≤?或1211m m m ->??-≤? ,解第一个不等式组,它的解集为空集,解第二个不等式组,它的解集为:103m ≤< , 综上所述:实数m 的取值范围为[0,)+∞. 9.设集合{}1,0,3A =-,{}3,21B a a =++,{}3A B ?=,则实数a 的值为________, 【解析】由题意,33a +=或213a +=,所以0a =或1,经检验,0a =或1都满足题目要求, 所以0a =或1。 10.已知集合{}1,2A =,{} 2,3B a a =+,若A B={1}?则实数a 的值为________ 【解析】由题意1B ∈,显然233a +≥,所以1a =,此时234a +=,满足题意,故答案为1, 题型:求集合的并集 1、简单求解 1.已知集合{0,1}A =,{0,1,2,3}B =,则A B 中的元素个数为________. 【解析】由已知可得:{}0,1,2,3A B ?=,则A B 中的元素个数为4.故答案为:4 3、求参数 1.设集合{}{} 23,0,3,1A B t t =-=-+,若A B A ?=,则t 的值为( ) A .1- B .2 C .1 D .2或1- 【解析】由A B A ?=知2,13B A t t ?∴-+=-①,即240t t -+=,①无解; 或210t t -+=②,②无解;或2213,20t t t t -+=--=,解得2t =或1t =-.故选:D. 3. 已知集合{A =,{}1,B m =,若A B A ?=,则m =( ) A .0 B .0或3 C .1 D .1或3 【解析】因为A B A ?=,所以B A ?,所以3m = 或m = 若3m = ,则{{1,3}A B ==,满足A B A ?=. 若m =0m =或1m =.若0m =,则{1,3,0},{1,3,0}A B ==,满足A B A ?=.若1m =,{1,3,1},{1,1}A B ==显然不成立,综上0m =或3m =,选B. 4.已知{}{}2512A x x B x m x m =-≤≤=+≤≤,,若A B A ?=,求实数m 的取值范围. 【解析】A B A B A =∴? 当B φ=时,121m m m +>∴< ;当B φ≠时,12512 1225m m m m m +≤??+≥-∴≤≤??≤? 综上所述m 的取值范围为5,2 ? ?-∞ ??? 5.已知集合{|12}A x x =≤≤,集合{|}B x x a =≥,若A B B ?=,则实数a 的取值范围是_______. 【解析】若A B B ?=则A ?B ,又集合{|12}A x x =≤≤,集合{|}B x x a =≥,所以1a ≤. 故答案为 1.a ≤ 题型:求集合的补集 3、简单求补集 1.设集合{}{}1,3,5,7,9,11,5,9==A B ,则 A B =( ) A .{}5,9 B .{}1,3,7,11 C .{}1,3,7,9,11 D .{}1,3,5,7,9,11 【解析】由补集的定义得A B ={}1,3,7,11.故选:B 2.已知集合U ={-2,-1,0,1,2},A ={0,1,2},则?U A =( ) A .{}2,1,0-- B .{}2,1-- C .{0,1,2} D .{}1,2 【解析】集合U ={-2,-1,0,1,2},A ={0,1,2},所以?U A ={-2,-1}.故选:B . 3.设集合A ={0,2,4,6,8,10},B ={4,8},则?A B = A .{4,8} B .{0,2,6} C .{0,2,6,10} D .{0,2,4,6,8,10} 【解析】由补集的概念,得?A B ={0,2,6,10},故选C . 4.设全集U =R ,集合{|3A x x =>或1}x <,则U A __. 【解析】∵全集U =R ,集合{|3A x x =>或1}x <,∴ {|13}U A x x =≤≤, 故答案为:{|13}x x ≤≤. 5.已知全集U =R ,集合{|2A x x =<-或2}x >,则U A ( ) A .(2,2)- B .(,2)(2,)-∞-+∞ C .[2,2]- D .(,2][24,)-∞-+∞ 【解析】由于集合{|2A x x =<-或2}x >,所以 U A [2,2]-.故选:C 4、求参数 1.设全集{}25,3,4U a a =+-,U 的子集{|2|,5}A a =+.如果 {3}U A =,求实数a 的值. 【解析】由题意{3}U A =,{} 25,3,4U a a =+-,{|2|,5}A a =+ 则2332a a a +-=?=或3a =-,当2a =时,{4,5}A =满足A 是U 的子集; 当3a =-时,{1,5}A =不满足A 是U 的子集,所以舍去.综上,2a = 2.设集合{}0,1,2,3U =,集合{} 2|0A x U x mx =∈+=,若{}1,2U C A =,则实数m =_____. 【解析】因为集合{}0,1,2,3U =, {}1,2U C A =,A={0,3},故m= -3. 3.设全集{}22,3,3U a a =+-,集合{} ,3A a =,{}2U C A =,则a =___________. 【解析】由{}2U C A =,{}22,3,3U a a =+-可知{}23,3A a a =+-,即{}{} 2 3,3,3a a a +-=. 故232,3a a a a ?+-=??≠?? .当0a ≥时,23a a a a +-=?=当0a <时,23a a a +-=-即 ()()2 230130a a a a +-=?-+=,故3a =-.不满足2,3a ≠.故a =