第1个回答 2018-11-26
有10个，答案如下图。
第2个回答 2018-11-25
10个
第3个回答 2018-11-25
5-1 = 4 ∈ A =>(5,1) ∈B
5-2 = 3 ∈ A =>(5,2) ∈B
5-3 = 2 ∈ A =>(5,3) ∈B
5-4 = 1 ∈ A =>(5,4) ∈B
4-1 = 3 ∈ A =>(4,1) ∈B
4-2 = 2 ∈ A =>(4,2) ∈B
4-3 = 1 ∈ A =>(4,3) ∈B
3-1 = 2 ∈ A =>(3,1) ∈B
3-2 = 1 ∈ A =>(3,2) ∈B
2-1 = 1 ∈ A =>(2,1) ∈B
B的元素个数 =1+2+3+4 =10本回答被提问者采纳
5-2 = 3 ∈ A =>(5,2) ∈B
5-3 = 2 ∈ A =>(5,3) ∈B
5-4 = 1 ∈ A =>(5,4) ∈B
4-1 = 3 ∈ A =>(4,1) ∈B
4-2 = 2 ∈ A =>(4,2) ∈B
4-3 = 1 ∈ A =>(4,3) ∈B
3-1 = 2 ∈ A =>(3,1) ∈B
3-2 = 1 ∈ A =>(3,2) ∈B
2-1 = 1 ∈ A =>(2,1) ∈B
B的元素个数 =1+2+3+4 =10本回答被提问者采纳
第4个回答 2018-11-25
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