| (x+y)2 |
| (x-y)(x+y) |
| -4xy |
| (x-y)(x+y) |
| (x+3y)(x-3y) |
| (x+3y)(x-y) |
| x-3y |
| x+y |
由已知得(3x-2y)(x+y)=0,
因为x+y≠0,所以3x-2y=0,即x=
| 2 |
| 3 |
所以原式=
| x-3y |
| x+y |
| ||
|
-
| ||
|
| 7 |
| 5 |
| x+y |
| x-y |
| 4xy |
| y2-x2 |
| x2+2xy-3y2 |
| x2-9y2 |
| (x+y)2 |
| (x-y)(x+y) |
| -4xy |
| (x-y)(x+y) |
| (x+3y)(x-3y) |
| (x+3y)(x-y) |
| x-3y |
| x+y |
| 2 |
| 3 |
| x-3y |
| x+y |
| ||
|
-
| ||
|
| 7 |
| 5 |