设各项均为正数的无穷数列an和bn满足2bn=an+an+1且an-1方=bn*bn+1,求证根号bn是等差数列
设各项均为正数的无穷数列an和bn满足2bn=an+an+1且an-1方=bn*bn+1,求证根号bn是等差数列
a1=1,a2=2求an和bn的通项公式
a1=1,a2=2求an和bn的通项公式
数学人气:914 ℃时间:2019-10-10 04:54:30
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题意:an+an+1=2bn; (1) bnbn+1=an+1*an+1 (2)(2)式两边开方得:an+1=sqrt(bn)*sqrt(bn+1) (3)(1)式两边平方,展开,然后将(3)式代入,可得:bn*bn-1+bn*bn+1+2*sqrt(bn-1*bn*bn*bn+1)=4bn*bn (4)整理(4)式后可得...
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