题目内容
已知:a+
=3,则a2+
=______;a-
=______.
| 1 |
| a |
| 1 |
| a2 |
| 1 |
| a |
∵a+
=3,a2+
=(a+
)2-2,
∴原式=32-2=7,
∵(a-
)2=(a+
)2-4=9-4=5,
∴±
.
故答案为:7,±
.
| 1 |
| a |
| 1 |
| a2 |
| 1 |
| a |
∴原式=32-2=7,
∵(a-
| 1 |
| a |
| 1 |
| a |
∴±
| 5 |
故答案为:7,±
| 5 |
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