17.
?2,4? 解析 由题意?1?x?3?1,即2?x?4,则解集为?2,4?.
18.(2017江苏01)已知集合A??1,2?,B?a,a2?3,若A为 .
18.解析 由题意a?33,故由A2??B??1?,则实数a的值
B??1?,得a?1.故填1.
19.(2017天津理1)设集合A??1,2,6?,B??2,4?,C??x?R|?1x5?,则
?AB?C?( ).
A.?2? B.?1,2,4? C.?1,2,4,6? D.?x?R|?1x5? 19.解析 因为A?{1,2,6},B?{2,4},所以A从而(AB?{1,2,6}{2,4}?{1,2,4,6},
B)C?{1,2,4,6}[?1,5]?{1,2,4}.故选B.
20.(2017北京理1)若集合A.D.
A??x–2 B??xx?–1或x?3?,则AB?( ). ?x–2 ?x–2 ?x–1 ?x1 AB??x?2?x??1?20.解析 画出数轴图如图所示,则.故选A. -2-113 x21.(2017全国1理1)已知集合A?xx?1,B?x3?1,则( ). A. A????B??xx?0? B. AB?R C. AB??xx?1? D. AB?? A??xx?1?21.解析 故选A. , B??x3x?1???xx?0?,所以 AB??xx?0?, AB??xx?1?. 22.(2017全国2理2)设集合A??1,2,4?,B?xx?4x?m?0.若A2??B?1,则B?( ). A.?1,?3? B.?1,0? C.?1,3? D.?1,5? 23.(2017浙江理1)已知集合P?x?1?x?1,Q?x0?x?2,那么PA.??1,2? B.?01,? C.??1,0? D.?1,2? 23.解析 P ????Q?( ). Q是取P,Q集合的所有元素,即?1?x?2.故选A.