已知数列{an}满足a1=1.an+1an+an+1=an(n≥1).数列{bn}满足bn=lna.证明数列an分之一是
1个回答
an+1an+an+1=an
等式两边同除以an+1an
1/(an+1)-1/an=1
{1/an}成等差数列,
1/an=1/a1+(n-1)=n
an=1/n
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