如题所述
a(n+1)=2an/(6an+1)
两边倒数
1/a(n+1)=(6an+1)/(2an)
=3 + 1/(2an)
1/a(n+1) + 3 = 2( 1/an + 3)
=> { 1/an + 3} 是等比数列,q=2
1/an + 3 = 2^(n-1).( 1/a1 + 3)
=5.2^n
1/an = -3 +5.2^n
an = 1/(-3 +5.2^n)
数列an的通项公式
an=1/(-3 +5.2^n)