题目内容
若x=
，y=
，则(
-
)
= ．
| 3 |
| 2 |
| 1 |
| y |
| 1 |
| x |
| xy |
| x2-2xy+y2 |
分析：先将(
-
)
作适当变形，再将相关值代入求解．
| 1 |
| y |
| 1 |
| x |
| xy |
| x2-2xy+y2 |
解答：解：(
-
)
=
=
=
=
+
故答案为：
+
| 1 |
| y |
| 1 |
| x |
| xy |
| x2-2xy+y2 |
| x-y |
| xy |
| xy |
| (x-y)2 |
| 1 |
| x-y |
| 1 | ||||
|
| 3 |
| 2 |
故答案为：
| 2 |
| 3 |
点评：本题主要考查代数的化简变形，再求值．要注意变形要等价变形．
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