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问题: 最小值

解答:

等比数列--->a1a2009 = a2a2008 = ... = a1005²
--->log2_a1+log2_a2+...+log2_a2009
 = log2_(a1a2...a2009) = 2009log2_a1005 = 2009
--->log2_a1005 = 1---->a1005=2--->a1a2009=4
--->log2_(a1+a2009)≥log2_[2√(a1a2009)] = 2.........C