等差数列An,Sn=na1+[n(n-1)]*d/2,类比等比数列Bn
问题描述:
等差数列An,Sn=na1+[n(n-1)]*d/2,类比等比数列Bn
答
无法类比
等比数列的前n项和
(1)q=1, Sn=na1
(2) q≠1 Sn=a1(1-q^n)/(1-q)
答
Tn=(a1)^n*q^(1+n-1)n/2
Tn为Bn前n项积.