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数列an满足a1=1/3,a(n+1)=an^2/an^2-an+1,n=1,2.
1)求a2 a3 (2)求证a1+a2+.an=1/2-a(n-1)/1-a(n+1) (3)1/2-1/3^2n-1,
人气:187 ℃ 时间:2020-03-24 12:29:49
解答
(1)易知a2=1/7,a3=1/43 (2)因a(n+1)=an^2/(an^2-an+1)则1/a(n+1)=1/an^2-1/an+1(取倒数)令bn=1/an,易知b1=1/a1=3则有b(n+1)=bn^2-bn+1即有1/[b(n+1)-1]=1/[bn(bn-1)]=1/(bn-1)-1/bn(移项、取倒数、裂式)即有1/bn...
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