题目内容
求数列1，3
，5
，…(2n-1)+
…的前n项和．
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 2n-1 |
1+3
+5
+…+(2n-1)+
=1+3+5+…+（2n-1）+
+
+…+
=n2+1-
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 2n-1 |
=1+3+5+…+（2n-1）+
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 2n-1 |
=n2+1-
| 1 |
| 2n-1 |
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题目内容
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 2n-1 |
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 2n-1 |
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 2n-1 |
| 1 |
| 2n-1 |