5,7,,4,9,25,( )
2023-06-09
A.72
B.256
C.49
D.169
参考答案:B
B.256
C.49
D.169
参考答案:B
【思路点拨】7-5=2,2的2次方=4, 4-7=(-3),(-3)的2次方=9;9-4=5,5的2次方=25,归纳假设数列通项an=(an-1-an-2)2,由此推演,未知项为(25-9)的2次方=256。故应选择B选项。
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