若1÷x-1÷y=3,则分式﹙2x+3xy-2y﹚÷﹙x-2xy-y﹚的值为﹙ A 3÷5 B ﹣﹙3÷5﹚ C 1 D 12÷5
问题描述:
若1÷x-1÷y=3,则分式﹙2x+3xy-2y﹚÷﹙x-2xy-y﹚的值为﹙
A 3÷5 B ﹣﹙3÷5﹚ C 1 D 12÷5
答
1÷x-1÷y=3 y-x=3xy (2x+3xy-2y)÷(x-2xy-y) =(2(x-y)+3xy)÷((x-y)-2xy) =(-6xy+3xy)÷(-3xy-2xy) =-3xy÷(-5xy) =3/5