已知数列{an}满足a1=0,an+1=(an-根号3)/(根号3an+1) (n属于N+),则该数列中a20=____

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已知数列{an}满足a1=0,an+1=(an-根号3)/(根号3an+1)(n属于N+),则该数列中a20=____已知数列{an}满足a1=0,an+1=(an-根号3)/(根号3an+1)(n属

已知数列{an}满足a1=0,an+1=(an-根号3)/(根号3an+1) (n属于N+),则该数列中a20=____
已知数列{an}满足a1=0,an+1=(an-根号3)/(根号3an+1) (n属于N+),则该数列中a20=____

已知数列{an}满足a1=0,an+1=(an-根号3)/(根号3an+1) (n属于N+),则该数列中a20=____
由a1=0 与a(n+1)=(an-sqr(3))/(sqr(3)an+1)得a2=-sqr(3)
由a(n+1)=(an-sqr(3))/(sqr(3)an+1)
得a(n+2)=(a(n+1)-sqr(3))/(sqr(3)a(n+1)+1)
=-(an+sqr(3))/(sqr(3)an-1)=-a(n-1)
把n用n+1去代得到
a(n+3)=-an
于是a(n+6)=-a(n+3)=an
于是an是以6为周期的周期数列
于是a20=a(3*6+2)=a2=-sqr(3)