好像很难的样

求大神

整理得,
(a(n+1))^2+(an)^2-22an*a(n+1)-10a(n+1)-10an+25=0
(a(n+2))^2+(a(n+1))^2-22a(n+1)*a(n+2)-10a(n+2)-10a(n+1)+25=0
比较两式可知,an,a(n+2)是方程
x^2-(22a(n+1)+10)x+(a(n+1))^2-10a(n+1)+25=0 的两根
an+a(n+2)=22a(n+1)+10
记bn=(1/2)+an,
b(n+2)=22b(n+1)-bn
其中b(0)=1/2,b(1)=11/2
然后……