题干
化简：
+
﹣
．
| a |
| + |
| 1 |
| a |
| 2 |
| + |
| 1 |
| ( |
| a |
| + |
| 1 |
| ) |
| 3 |
| a |
| 4 |
| − |
| 1 |
| a |
| − |
| 3 |
| a |
| + |
| 1 |
答案(点此获取答案解析）
解：原式=
+
| a |
| + |
| 1 |
| a |
| 2 |
| + |
| 1 |
