题目内容
数列{an}的通项公式为an=
，则该数列的前n项和Sn=______．
| 1 |
| (n+1)(n+2) |
an=
=
-
∴Sn=(
-
)+(
-
)+(
-
)+…+（
-
）=
-
=
．
故答案为
| 1 |
| (n+1)(n+2) |
| 1 |
| n+1 |
| 1 |
| n+2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| n+1 |
| 1 |
| n+2 |
| 1 |
| 2 |
| 1 |
| n+2 |
| n |
| 2(n+2) |
故答案为
| n |
| 2(n+2) |
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