| a−b |
| a+2b |
| a2−b2 |
| a2+4ab+4b2 |
| a−b |
| a+2b |
| (a+2b)2 |
| (a+b)(a−b) |
=
| a+2b |
| a+b |
| a+b |
| a+b |
| a+2b−a−b |
| a+b |
| b |
| a+b |
当a=b=2时，原式=
| 2 |
| 2+2 |
| 2 |
| 4 |
| 1 |
| 2 |
或当a=1，b=-2时，原式=
| −2 |
| 1−2 |
| a−b |
| a+2b |
| a2−b2 |
| a2+4ab+4b2 |
| a−b |
| a+2b |
| a2−b2 |
| a2+4ab+4b2 |
| a−b |
| a+2b |
| (a+2b)2 |
| (a+b)(a−b) |
| a+2b |
| a+b |
| a+b |
| a+b |
| a+2b−a−b |
| a+b |
| b |
| a+b |
| 2 |
| 2+2 |
| 2 |
| 4 |
| 1 |
| 2 |
| −2 |
| 1−2 |