作业帮 > 数学 > 作业

等差数列{a¬n}中,S¬30=50,S¬50=30则S¬80等于多少?

来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/05/10 15:33:22
等差数列{a¬n}中,S¬30=50,S¬50=30则S¬80等于多少?
s(n)/n是等差数列
求吧
设bn=sn/n
b30=...
b50=...
b80=...
it‘s not fair it's not easy+? that's not your IT'S NOT REALLY It's not safe that's not well It's not very Love's not forget when it's not That's not the that\'s not it\'s not