题干
已知
=
=
，求
的值．
| a |
| + |
| b |
| 3 |
| b |
| + |
| c |
| 4 |
| c |
| + |
| a |
| 5 |
| a |
| - |
| b |
| - |
| c |
| c |
| - |
| a |
| + |
| b |
答案(点此获取答案解析）
解：设
=
| a |
| + |
| b |
| 3 |
| b |
| + |
| c |
| 4 |
