Question

高二数学数列问题

下列数列通项公式
(1) 3/2,5/4,7/8,9/16
(2) -3*7,4*8,-5*9,6*10
(3) 1/3,-1/15,1/35,-1/63
(4) 3/5,1/2,5/11,3/7,7/17
(5) 3,6,10,15
(6) 9,99,999,9999
(7) 1,1/3,1/5,1/7

Answer 1

1)2n+1/2^n(n为1,2,3....)
2)(-1)^n*(n+2)^(n+6) 注，我写的^代表次方
3）(-1)^(n+1)*1/{(4n^2)-1}
4)(n+2)/(3n+2)
5)1+2+3+....+n=n!(n的阶乘)
6）(10^n)-1
7)1/(2n-1)

Answer 2

写出下列数列通项公式：

(1) 3/2,5/4,7/8,9/16,......
通项公式：An = (2n+1)/2^n

(2) -3*7,4*8,-5*9,6*10,......
通项公式：An = [(-1)^n](n+2)(n+6)

(3) 1/3,-1/15,1/35,-1/63,......
通项公式：An = [(-1)^(n+1)]/[4n²-1]

(4) 3/5,1/2,5/11,3/7,7/17,......
通项公式：An = (n+2)/(3n+2)

(5) 3,6,10,15,......
通项公式：An = 3+(½n+2)(n-1) = n²/2 + 3n/2 + 1

(6) 9,99,999,9999,......
通项公式：An = 10^n - 1

(7) 1,1/3,1/5,1/7,......
通项公式：An = 1/(2n-1)

Answer 3

an=2n+1/2^n
an=(-1)^n*(n+2)/n+6
an=(-1)^(n+1) /(4n^2-1)
an=(n+2)/(3n+2)
an=(n^2+3n+2)/2
an=10^n -1
an=1/(2n-1)

Answer 4

1. An=(2n+1)/(2^n)
2.An=(-1)^n*(n+2)*(n+5)
3.An=(-1)^(n-1) /(n*(n+2))
4.An=(n+2)/(3n+2)
5.An=2n+2^(n-1)
6.An=10^n -1
7.An=1/(2n-1)

Answer 5

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