题干
已知
=
=
，且abc≠0，则
=____．
| a |
| 2 |
| b |
| 4 |
| c |
| 5 |
| a |
| + |
| 2 |
| c |
| 2 |
| b |
| a |
| + |
| c |
| b |
答案(点此获取答案解析）
| 4 |
| 3 |
