问题
填空题
在等比数列{an}中,a1=
|
答案
q=
=3 a4 a1
=-2,3 -8
|a1|+|a2|+…+|an|=
=2n-1-
(1-2n)1 2 1-2 1 2
故答案为:-2,2n-1-1 2
在等比数列{an}中,a1=
|
q=
=3 a4 a1
=-2,3 -8
|a1|+|a2|+…+|an|=
=2n-1-
(1-2n)1 2 1-2 1 2
故答案为:-2,2n-1-1 2
将下面的句子填入适当的位置,使对话完整。(5分)
B: ①________ A: ②________ B: No. I'm not. I'm going to sing rock music. A: ③________ B: I'm going to take singing lessons. A: When are you going to start? B: ④________ A: ⑤________ B: In New York. |