已知数列{an}和{Bn}满足a1=2 an-1=an(an+1-1) bn=an-1 n∈N+
问题描述:
已知数列{an}和{Bn}满足a1=2 an-1=an(an+1-1) bn=an-1 n∈N+
已知数列{an}和{Bn}满足a1=2 an-1=an[a(n+1)-1] bn=an-1 n∈N+
(1)求Bn通向公式
(2)设Cn=B(2n-1)B(2n+1) 求使得C1+C2+.+Cn(3)设Bn前n项和为Sn,Tn=s2n-sn 比较T(n+1)和Tn大小
答
an-1=an[a(n+1)-1],an[a(n+1)-2]=-1,a(n+1)=2-1/an=1+(an-1)/an,a1=2,a2=1+1/2=3/2,a3=1+(3/2-1)/(3/2)=4/3,------,an=1+(n/(n-1)-1)/(n/(n-1))=(n+1)/n;bn=an-1=(n+1)/n-1=1/n;cn=B(2n-1)B(2n+1) =1/(2n-...