已知 1/x-1/y=5.求(2x+4xy-2y)/(x-3xy-y)
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已知 1/x-1/y=5.求(2x+4xy-2y)/(x-3xy-y)
已知 1/x-1/y=5.求(2x+4xy-2y)/(x-3xy-y)
已知 1/x-1/y=5.求(2x+4xy-2y)/(x-3xy-y)
1/x-1/y=5
(y-x)/xy=5
y-x=5xy
(2x+4xy-2y)/(x-3xy-y)
=[4xy-2(y-x)]/[-3xy-(y-x)]
=(4xy-10xy)/(-3xy-5xy)
=(-6)/(-8)
=3/4
(2x+4xy-2y)/(x-3xy-y)分子分母同除以xy
得 (2/y+4-2/x)
分数线
(1/y-3-1/x)
得 2(1/y-1/x)+4
分数线
(1/y-1/x)-3
因为1/x-1/y=5
所以1/y-1/x=-5
代入 2(1/y-1/x)+4...
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(2x+4xy-2y)/(x-3xy-y)分子分母同除以xy
得 (2/y+4-2/x)
分数线
(1/y-3-1/x)
得 2(1/y-1/x)+4
分数线
(1/y-1/x)-3
因为1/x-1/y=5
所以1/y-1/x=-5
代入 2(1/y-1/x)+4
分数线
(1/y-1/x)-3
得 2*(-5)+4
分数线 =3/4
-5-3
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