题目内容
已知
=
+
,则M=______.
| M |
| x2-y2 |
| 2xy-y2 |
| x2-y2 |
| x-y |
| x+y |
∵
=
+
,
=
,
即
=
.
∴M=x2.
| M |
| x2-y2 |
| 2xy-y2 |
| x2-y2 |
| (x-y)2 |
| x2-y2 |
| M |
| x2-y2 |
| 2xy-y2+x2-2xy+y2 |
| x2-y2 |
即
| M |
| x2-y2 |
| x2 |
| x2-y2 |
∴M=x2.
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