x2 |
m+2 |
y2 |
9-m |
|
A.命题“若x2=1,则x=1”的否命题为:“若x2=1,则x≠1” |
B.“x=6”是“x2-5x-6=0”的必要不充分条件 |
C.命题“对任意x∈R,均有x2-x+1>0”的否定是:“存在x∈R使得x2-x+1<0” |
D.命题“若x=y,则cosx=cosy”的逆否命题为真命题 |
A.0 | B.1 | C.2 | D.3 |
π |
2 |
A.a,b∈R,且a>b,则a2>b2 | ||||
B.若a>b,c>d,则
| ||||
C.a,b∈R,且ab≠0,则
| ||||
D.a,b∈R,且a>|b|,则an>bn(n∈N*) |
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