题目内容
已知x=
,y=
,求3x2-5xy+3y2的值.
| ||
2 |
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2 |
∵x=
,y=
,
∴x+y=
,xy=
,
∴原式=3(x+y)2-11xy
=3×(
)2-11×
=
.
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2 |
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∴x+y=
3 |
1 |
2 |
∴原式=3(x+y)2-11xy
=3×(
3 |
1 |
2 |
=
7 |
2 |
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