A.∃x∈R,f(x)≤f(x0) | B.∃x∈R,f(x)≥f(x0) |
C.∀x∈R,f(x)≤f(x0) | D.∀x∈R,f(x)≥f(x0) |
b |
2a |
b |
2a |
A.若m∥α,n∥β且α∥β,则m∥n | B.若m⊥α,n⊥β且α⊥β,则m⊥n |
C.若m∥α,n⊥β且α⊥β,则m∥n | D.若m⊂α,n⊂β,m∥n,则α∥β |
A.0 | B.1 | C.2 | D.3 |
A.∀x∈(0,π),均有sinx>cosx | ||
B.命题“∃x∈R使得x2+x+1<0”的否定是:“∀x∈R,均有x2+x+1<0” | ||
C.“a=0”是“函数f(x)=x3+ax2+x为奇函数”的充要条件 | ||
D.∃x∈R,使得sinx+cosx=
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