有關A123Bxyx的精選大全

已知*A={1,2,3},B={(x,y)|x∈A,y∈A,x+y∈A},則*B的子集的個數為(  )(A...
問題詳情:已知*A={1,2,3},B={(x,y)|x∈A,y∈A,x+y∈A},則*B的子集的個數為()(A)4   (B)7   (C)8   (D)16 【回答】C解析:因為*A={1,2,3},B={(x,y)|x∈A,y∈A,x+y∈A},所以*B={(1,1),(1,2),(2,1)},*B的子集的...
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