> 数学 >
已知(4x-2y-1)2+
xy−2
=0,求2x2y-4x2y2-xy2的值.
人气:152 ℃ 时间:2019-10-24 09:15:03
解答
∵(4x-2y-1)2+
xy−2
=0,
∴4x-2y-1=0,得:2x-y=
1
2

xy-2=0,得:xy=2,
2x2y-4x2y2-xy2=xy(2x-y)-4(xy)2
当2x-y=
1
2
,xy=2,
上式=2×
1
2
-4×22
=-15.
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