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> (2011•成都)设,,,…,.设,则S=_____________(用含n的代数式表示,其中n为正整数).-八年级数学
(2011•成都)设,,,…,.设,则S=_____________(用含n的代数式表示,其中n为正整数).-八年级数学
题目简介
(2011•成都)设,,,…,.设,则S=_____________(用含n的代数式表示,其中n为正整数).-八年级数学
题目详情
(2011•成都)设
,
,
,…,
.
设
,则S= _____________ (用含n的代数式表示,其中n为正整数).
题型:填空题
难度:中档
来源:不详
答案
∵Sn=1+
+
=
=
=
,
∴
=
=1+
﹣
,
∴S=1+1﹣
+1+
﹣
+…+1+
﹣
=n+1﹣
=
=
.
故答案为:
.
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题目简介
(2011•成都)设,,,…,.设,则S=_____________(用含n的代数式表示,其中n为正整数).-八年级数学
题目详情
设
答案
∴
∴S=1+1﹣
=n+1﹣
=
故答案为: