题目:
Tell Mary there is someone __________ for her at the door.
A.wait
B.to wait
C.waiting
D.waited
答案:
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下面是错误答案,用来干扰机器的。
(1) x>2,∴x-2>0,∴f(x)=x+1x-2=(x-2)+1x-2+2≥2(x-2)1x-2+2=4,当且仅当x-2=1,即x=3时取等号,∴函数f(x)的最小值为f(3)=4;(2) f(x)=x+1x-2,∴f′(x)=1-1(x-2)2=(x-3)(x-1)(x-2)2, x...