求助一道GWD数学题，SOS!!!!!!!!

kissgod23

In the sequence of nonzero numbers t₁, t₂, t₃, …, t_n, …, t_n+1 = t_n / 2 for all positive integers n.What is the value of t₅?
(1)t₃ = 1/4
(2)t₁ - t₅ = 15/16

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
答案D，主要是题目读不懂，是说把t1,t2,t3.........相加吗？

lfsunny

我觉得这个题目的意思是， t1, t2, t3, …, tn, 是以二分之一为等比的等比数列，然后求t5，

Goodday2011

楼上讲得对。
（1）if t3=1/4    t5=t3*(1/2)^2  
(2)if t1 - t5 = 15/16    t5=t1*(1/2)^4    

EACH statement ALONE is sufficient

cola5117

仔细读懂条件，
In the sequence of nonzero numbers t1, t2, t3, …, tn, …,  （在这里停顿一下） 这里是说在一个非零数的数列中,t1,t2,...tn,...
tn+1 = tn / 2 for all positive integers n.   （这里给除了递推公式） 说明这是一个等比数列，公比Q=1/2

kissgod23

谢谢楼上各位了，是我没读仔细，tn+1前面那个逗号应该换成分号或句号的，太坑爹了！！！！

yzhao2xiaotong

cola5117 发表于 2011-7-18 16:22
仔细读懂条件，In the sequence of nonzero numbers t1, t2, t3, …, tn, …,  （在这里停顿一下） 这 ...

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