在等差数列{an}中,a1=-28,公差d=4,若前n项和Sn取得最小值,则n的 发布时间:2017-04-26 17:40 │ 来源:www.tikuol.com 题型:选择题 问题: 在等差数列{an}中,a1=-28,公差d=4,若前n项和Sn取得最小值,则n的值为( )A.7B.8 C.7或8D.8或9
题型:选择题 Most of the older civilizations which flourished during the fifth century B.C. are died out .A.they have died outB.has died outC.have died outD.they had died out 查看答案