已知图1是一个边长为1的正三角形,三边中点的连线将它分成四个小三角形,去掉中间的一个小三角形,得到图2,再对图2中剩下的三个小三角形重复前述操作,得到图3,重复这种操作可以得到一系列图形.记第n个图形中所有剩下的小三角形的面积之和为an,所以去掉的三角形的周长之和为bn.
(I) 试求 a4, b4;
(II)试求 an , bn .
暂无解析
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不等式的解集是()
已知集合M=0,1,2B=1,4,那么集合AUB等于
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