| a−2 |
| a−1 |
| a(a−1) |
| (a−2)2 |
=
| a |
| a−2 |
当a=1时，原式=
| 1 |
| 1−2 |
（2）原式=
| (x−1)(x+1)−x(x−2) |
| x(x+1) |
| (x+1)2 |
| x(2x−1) |
=
| 2x−1 |
| x(x+1) |
| (x+1)2 |
| x(2x−1) |
=
| x+1 |
| x2 |
∵x满足x2-x-1=0，
∴x2=x+1，
∴原式=
| x+1 |
| x+1 |
| 1 |
| a−1 |
| a2−4a+4 |
| a2−a |
| x−1 |
| x |
| x−2 |
| x+1 |
| 2x2−x |
| x2+2x+1 |
| a−2 |
| a−1 |
| a(a−1) |
| (a−2)2 |
| a |
| a−2 |
| 1 |
| 1−2 |
| (x−1)(x+1)−x(x−2) |
| x(x+1) |
| (x+1)2 |
| x(2x−1) |
| 2x−1 |
| x(x+1) |
| (x+1)2 |
| x(2x−1) |
| x+1 |
| x2 |
| x+1 |
| x+1 |