已知数列{an}满足a1=33，an+1-an=2n，则ann的最小值为（）A.233-1B.535C.212D.232

Question

_n1n+1n(an)/(n)的最小值为（　　）
A. 2√(33)-1
B. (53)/(5)
C. (21)/(2)
D. (23)/(2)(an)/(n)anananannnn
√(33)-1
B. (53)/(5)
C. (21)/(2)
D. (23)/(2)√(33)

33

33
(53)/(5)
C. (21)/(2)
D. (23)/(2)(53)/(5)535355
(21)/(2)
D. (23)/(2)(21)/(2)212122
(23)/(2)(23)/(2)232322

Answer 1

由题意可得an=（an-an-1）+（an-1-an-2）+…+（a2-a1）+a1=2（n-1）+2（n-2）+…+2+33=[2(n−1)+2](n−1)2+33=n2-n+33，故ann=n2−n+33n=n+33n-1由于函数y=x+33x在（0，33）单调递减，在（33，+∞）单调递增，故当an...