题目内容
5.若,,则的元素个数为(A)0 (B)1 (C)2 (D)3
答案:C
解析:化简A={x∈Z|21≤22-x<23}
={x∈Z|1≤2-x<3}
={x∈Z|-1<x≤1}
={0,1},
B={x∈R||log2x|>1}
={x∈R|log2x>1或log2x<-1=
={x|x>2或0<x<},
∴RB={x|x≤0或≤x≤2}.
∴A∩(RB)={0,1}.故选C.
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题目内容
5.若,,则的元素个数为(A)0 (B)1 (C)2 (D)3
答案:C
解析:化简A={x∈Z|21≤22-x<23}
={x∈Z|1≤2-x<3}
={x∈Z|-1<x≤1}
={0,1},
B={x∈R||log2x|>1}
={x∈R|log2x>1或log2x<-1=
={x|x>2或0<x<},
∴RB={x|x≤0或≤x≤2}.
∴A∩(RB)={0,1}.故选C.