已知：X分之一减去Y分之一等于3，求2x-3xy-2y除以-x+xy+y的值是多少？

写过程

1/x-1/y=3

y-x=3xy

x-y=-3xy

(2x-3xy-2y)/(-x+xy+y)

=[2(x-y)-3xy]/[-(x-y)+xy]

=(-6xy-3xy)/(3xy+xy)

=(-9xy)/(4xy)

=-9/4

x分之一减y分之一等于3,两边同时乘以xy得y减x等于负3xy.2x-3xy-2y除以-x+xy+y等于-6xy-3xy除以3xy+xy结果等于-4分之9

X分之一减去Y分之一等于3

1/x-1/y=3

得XY=3(Y-X)

2x-3xy-2y/(x+xy+y)=(11X-11Y)/(-4X+4Y)=-11/4

应该没算错吧= =

2x-3xy-2y除以-x+xy+y

= - 【（2x-3xy-2y）/(x-xy-y)】

=-[2(x-xy-y)-xy]/(x-xy-y)

= - 2 +xy/(x-xy-y)

xy/(x-xy-y)的倒数是

(x-xy-y)/xy=1/y-1-1/x=-(1/x-1/y)-1=-3-1=-4 所以xy/(x-xy-y)=-1/4

所以原式=-2-1/4= -9/4

1/x-1/y=3

(y-x)/xy=3

y-x=3xy

(2x-3xy-2y)可以化简成-9xy

(-x+xy+y)可以化成4xy

所以结果是-9/4

2x-3xy-2y

分子分母同除以XY

=2/Y-3-2/X

2/3-3=-7/3

-x+xy+y=-3+1=-2

解：

因为1/x-(1/y)=3【两边同时乘以xy】

所以y-x=3xy

所以x-y=-3xy

(2x-3xy-2y)÷(-x+xy+y)

=[2(x-y)-3xy]÷[-(x-y)+xy]

将x-y=-3xy代入上面式子，

=[2×(-3xy)-3xy]÷[3xy+xy]

=-9xy/4xy

=-9/4