题干
若a+b=1，且a≠0，求（a+
）÷
的值．
| 2 |
| a |
| b |
| + |
| b |
| 2 |
| a |
| a |
| + |
| b |
| a |
| 2 |
| a |
| b |
| + |
| b |
| 2 |
| a |
| a |
| + |
| b |
| a |
