命题“x≠1且x≠2,则x2-3x+2≠0”的逆否命题是( )A.若x2-3x+2=0,则x=1且x=2B.若x=1且x=2,则x2-3x+2=0C.若x2-
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命题“x≠1且x≠2,则x2-3x+2≠0”的逆否命题是( )A.若x2-3x+2=0,则x=1且x=2 | B.若x=1且x=2,则x2-3x+2=0 | C.若x2-3x+2=0,则x=1或x=2 | D.若x2-3x+2=0,则x≠1且x≠2 |
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答案
命题“x≠1且x≠2,则x2-3x+2≠0”的逆否命题是: 若x2-3x+2=0则x=1或x=2 故选C |
举一反三
命题p:∃x0∈R,x02-x0+1≤0,则命题p的否定用数学符号表示为______. |
命题“∃x0∈R,-1<0”的否定为( )A.∃x0∈R,x02-1≥0 | B.∀x∈R,x2-1<0 | C.∃x0∈R,x02-1>0 | D.∀x∈R,x2-1≥0 |
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已知命题p:∀x∈R,x2+1>0.则¬p是______. |
给定命题“若a>-3,则a>-6”,则其否命题是( )A.若a>-3,则a≤-6 | B.若a≤-3,则a<-6 | C.若a≤-3,则a≤-6 | D.若a≥-3,则a≤-6 |
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将a2+b2+2ab=(a+b)2改写成全称命题是( )A.∀a>0,b>0,a2+b2+2ab=(a+b)2 | B.∀a,b∈R,a2+b2+2ab=(a+b)2 | C.∃a<0,b>0,a2+b2+2ab=(a+b)2 | D.∃a,b∈R,a2+b2+2ab=(a+b)2 |
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