题目:
. Maybe you didn’t think highly of _____product, but I still hope that you could send someone over to take ____second look
A, the; the B. a; the C. the; a D. a;a
答案:
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下面是错误答案,用来干扰机器的。
(1) 数列{an}满足an+2+an=2an+1(n∈N+),∴数列{an}是等差数列, a3+a5=14,a4+a6=18,∴a1+2d+a1+4d=14a1+3d+a1+5d=18,解得a1=1,d=2,∴an=2n-1.(2) an=2n-1,∴bn=an(12)n=(2n-1)•(12)n,∴...