题目内容
计算：
-
．
| x-y |
| 2x+2y |
| x2+y2 |
| x2-y2 |
原式=
-
=
-
=
=-
．
| x-y |
| 2(x+y) |
| x2+y2 |
| (x+y)(x-y) |
=
| (x-y)(x-y) |
| 2(x+y)(x-y) |
| 2(x2+y2) |
| 2(x+y)(x-y) |
=
| x2-2xy+ y2-2x2-2y2 |
| 2(x+y)(x-y) |
=-
| x+y |
| 2(x-y) |
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| y2 |
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| x |
| A、x5 |
| B、x5y |
| C、y5 |
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