| a2−1 |
| a2+4a+4 |
| a+1 |
| a+2 |
=
| (a+1)(a−1) |
| (a+2)2 |
| a+2 |
| a+1 |
=
| a−1 |
| a+2 |
（2）
| x−1 |
| x−2 |
| 1 |
| 2−x |
方程的两边同乘（x-2），得
x-1+x+2=-1，
解得x=-1．
检验：把x=-1代入（x-2）=-3≠0．
故原方程的解为：x=-1．
| a2−1 |
| a2+4a+4 |
| a+1 |
| a+2 |
| x−1 |
| x−2 |
| 1 |
| 2−x |
| a2−1 |
| a2+4a+4 |
| a+1 |
| a+2 |
| (a+1)(a−1) |
| (a+2)2 |
| a+2 |
| a+1 |
| a−1 |
| a+2 |
| x−1 |
| x−2 |
| 1 |
| 2−x |