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={0,1,2,3}, ={1,2,4},则集合A.∪B.= ( ) A.{0, 1,2,3,4}B.{1,2,3,4} {1,2} {0}
={x|(x﹣1)(x+2)>0},集合 ={﹣3,﹣2,﹣1,0,1,2},则A.∩B.等于( ) A.{0,1}B.{﹣3,﹣2} {﹣3,2} {﹣3,﹣2,1,2}
(-2,-1) (2,1) (3,-1) (-3,1)
1个 2个 3个 4个
={1,2,3,4}, ={x∈N||x|≤2},则A.∩B=( ) A.{1,2,3,4}B.{﹣2,﹣1,0,1,2,3,4} {1,2} {2,3,4}
2:3,3:2 3:2,2:3 1:1,3:2 2:3,1:1
(-2,-1) (2,1) (3,-1) (-3,1)
若a1+a2>0,则a2+a3>0 若a1+a3<0,则a1+a2<0 若0<a1<a2,则2a2<a1+a3 若a1<0,则(a2﹣a1)(a2﹣a3)>0
1:3:2 2:3:1 1:2:3 3:2:1 2:1:3
={0,1,2,3},B={1,2,4},则集合A.∪ = A.{0,1,2,3,4} B.{1,2,3,4} {1,2} {0}
2:3 3:2 3:2 2:3 1:1 3:2 2:3 1:1
1 2 3 4 1 1 2 3 4 2 1 2 3 4 3 1 2 3 4 0
3, 2, 1 2, 1, 3 3, 1, 2 1, 3, 2
2∶3 3∶2 3∶2 2∶3 1∶1 3∶2 2∶3 1∶1
2: 2 3: 2 3: 2 2: 3 1: 1 3: 2 2: 3 1: 1