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设集合A={-1,0,1},B={0,1,2},若x∈A,且xB,则x等于
A.-1 B.0 C.1 D.2
设a=(-2,1-cosθ),,且a//b,又0°<θ<90°,则θ等于
A.45°
B.30°
C.60°
D.30°或60°
设函数f(x)=logax(a>0且a≠1)满足f(9)=2,y=f-1(x)是y=f(x)的反函数,则f-1(loga2)等于
2
log2
设F1,F2是双曲线-y2 = 1 的两个焦点,点P在双曲线上,且·= 0,则||·||的值等于
A.2 B.2 C.4 D.8