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
命题“∀x∈R,x3-x2+1≤0”的否定是( )
A∃x∈R,x3-x2+1≥0
B∃x∈R,x3-x2+1>0
C∃x∈R,x3-x2+1≤O
D∀x∈R,x3-x2+1>0
命题“∃x∈R,ex<x”的否定是( )
A∃x∈R,ex>x
B∀x∈R,ex≥x
C∃x∈R,ex≥x
D∀x∈R,ex>x
已知命题p:∃x∈R,使aex+x<0,则¬p是( )
A∀x∈R,aex+x>0
B∀x∈R,aex+x≥0
C∃x∈R,aex+x≥0
D∃x∈R,aex+x>0
命题“∃数列{an},{bn}既是等差数列,又是等比数列”( )
A是特称命题并且是假命题
B是全称命题并且是假命题
C是特称命题并且是真命题
D是全称命题并且是真命题
扫码查看完整答案与解析