Question

大神们，这题怎么做啊！！跪求！！

Answer 1

如下图所示:

Answer 2

追答

最后一个，因为我的粗心出现了错误

Answer 3

33.S3-S2=A3=-8

S2=A1+A2=A1+A1q=2

A3=A1q²=-8

解得A1=-2,q=-2

34.Sn=n(n+1)/2,bn=1/Sn=2/n(n+1)=2［1/n-1/(n+1)］故Tn=2［1-1/2+1/2-1/3+……+1/(n-1)-1/n+1/n-1/(n+1)］=2［1-1/(n+1)］=2n/(n+1)

35.Sn=na1+n(n-1)/2*d

S5=5a1+10*3/2=15

解得a1=0,An=3(n-1)/2

bn=e∧(3/2*(n-1))

b(n+1)=e∧(3/2*n)

b(n+1)/bn=e∧(3/2n)/e∧(3/2(n-1))=e

b1=1,即数列bn为首项b1=1,公比q=e的等比数列

b1b2b3b4b5=b1*b1q*b1q²*b1q³*b1q∧4=(b1)∧5*q∧10=e∧10