题干
已知等式
=
−
，对任意正整数n都成立．计算：
+
+
+⋯+
=____．
| 1 |
| n |
| ( |
| n |
| + |
| 1 |
| ) |
| 1 |
| n |
| 1 |
| n |
| + |
| 1 |
| 1 |
| 1 |
| × |
| 2 |
| 1 |
| 2 |
| × |
| 3 |
| 1 |
| 3 |
| × |
| 4 |
| 1 |
| n |
| ( |
| n |
| + |
| 1 |
| ) |
答案(点此获取答案解析）
| n |
| n |
| + |
| 1 |
