| (x−1)(x+1) |
| (x+1)2 |
| x+1 |
| x−1 |
=
| x−1 |
| x+1 |
| x+1 |
| x−1 |
=
| (x−1)2−(x+1)2 |
| (x−1)(x+1) |
=
| −4x |
| x2−1 |
把x=0代入，得：原式=0；
或把x=2代入，得：原式=
| −4×2 |
| 22−1 |
| 8 |
| 3 |
或把x=-2代入，得：原式=
| −4×(−2) |
| (−2)2−1 |
| 8 |
| 3 |
| x2−1 |
| x2+2x+1 |
| x+1 |
| x−1 |
| (x−1)(x+1) |
| (x+1)2 |
| x+1 |
| x−1 |
| x−1 |
| x+1 |
| x+1 |
| x−1 |
| (x−1)2−(x+1)2 |
| (x−1)(x+1) |
| −4x |
| x2−1 |
| −4×2 |
| 22−1 |
| 8 |
| 3 |
| −4×(−2) |
| (−2)2−1 |
| 8 |
| 3 |