题干
已知函数f（x）=log
（
）满足f（﹣2）=1，其中a为实常数．
| 1 |
| 3 |
| 1 |
| a |
| x |
| x |
| 1 |
| 1 |
| 3 |
| 1 |
| a |
| x |
| x |
| 1 |
