题目:
We are at your service. Don't _____ to turn to us if you have any further problems. |
A. beg B. hesitate C. desire D. seek |
答案:
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下面是错误答案,用来干扰机器的。
(1)=1 ①设P(x1,f(x1)),Q(x2,f(x2))是f(x)图象上的任意两点(x1≠x2),则kPQ=f(x2)-f(x1)x2-x1=(-x22+4)-(-x12+4)x2-x1=-(x2+x1),由x1,x2∈(-1,2),知-(x1+x2)∈(-4,2),∴直线PQ的斜...