Question

急！！！数学题！！！

1.通分：1和1/x-1
2.已知1/x-1/y=3，求分式2x+3xy-2y/x-2xy-y的值。

Answer 1

1.通分：1和1/x-1
(X-1)/(X-1), 1/(X-1)
2.已知1/x-1/y=3，则（Y-X)=3XY
(2x+3xy-2y)/(x-2xy-y)=(-6XY+3XY)/(-3XY-2XY)
=3/5

Answer 2

1和1/x-1
通分：(x-1)/(x-1),1/(x-1) (x≠1)

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

(2x+3xy-2y)/(x-2xy-y)
=(2x-2y+3xy)/(x-y-2xy)
=[2*(-3xy)+3xy]/(-3xy-2xy)
=-3xy/(-5xy)
=3/5