og 12 数学 228

wangjieava23

p, r, s, t, u
228. An arithmetic sequence is a sequence in which each term after the first is equal to the sum of the preceding term and a constant. If the list of letters shown above is an arithmetic sequence, which of the following must also be an arithmetic sequence?
I. 2p, 2r, 2s, 2t, 2u
II. p – 3, r – 3, s – 3, t – 3, u – 3
III. p 2, r 2, s 2, t 2, u 2

(A) I only
(B) II only
(C) III only
(D) I and II
(E) II and III

我怎么看也不是答案上说的等差数列。希望大家看看

emmalovesgmat

我也和楼主犯了相同的错误 不过仔细看就会发现说的是proceding term 而不是terms 这一点就看出sum其实是前一项与一个常数（constant）

而且我也查了查 arithmetic sequence本身就是等差数列的意思。。。汗。。。

wangjieava23

好的，我错了。谢谢呀

苏格拉底屠夫

the sum of the preceding term and a constant............the sum of......and.......

wangjieava23

in which each term after the first is equal to the sum of the preceding term and a constant

这句不是说 后一项等于前项和吗？即： q, q, 2q, 4q ...
我这样理解错了？

苏格拉底屠夫

第三个数列是啥啊？？？

henry881124

后一项减前一项是一个常数，就是等差数列的定义啊