一道,数列题,
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一道,数列题,
一道,数列题,
一道,数列题,
a1=1/2
7a(n+1) = 3an -5n+6
a(n+1) + (5/4)(n+1) -59/16= (3/7)( an + (5/4)n -59/16)
{an + (5/4)n -59/16}是等比数列,q=3/7
an + (5/4)n -59/16 = (3/7)^(n-1) .(a1 + 5/4 -59/16)
=-(31/16).(3/7)^(n-1)
an =- (5/4)n +59/16 -(31/16).(3/7)^(n-1)