已知1x-1y=3,则5x+xy-5yx-xy-y的值为______.-数学

题目简介

已知1x-1y=3,则5x+xy-5yx-xy-y的值为______.-数学

题目详情

已知
1
x
-
1
y
=3,则
5x+xy-5y
x-xy-y
的值为______.
题型:填空题难度:偏易来源:不详

答案

class="stub"1
x
-class="stub"1
y
=class="stub"y-x
xy
=3,
∴y-x=3xy,即x-y=-3xy,
class="stub"5x+xy-5y
x-xy-y
=
5(x-y)+xy
(x-y)-xy
=class="stub"-15xy+xy
-3xy-xy
=class="stub"-14xy
-4xy
=class="stub"7
2

故答案为:class="stub"7
2

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