若数列{an}是等差数列,对于bn=1n(a1+a2+…+an),则数列{bn} 发布时间:2017-05-18 17:05 │ 来源:www.tikuol.com 题型:填空题 问题: 若数列{an}是等差数列,对于bn=1n(a1+a2+…+an),则数列{bn}也是等差数列.类比上述性质,若数列{cn}是各项都为正数的等比数列,对于dn>0,则dn=______时,数列{dn}也是等比数列.
题型:填空题 It's reported that the Underground Line No. 3 in our city in 2012. [ ]A. will built B. has built C. will be built D. has been built 查看答案