解法一:1)因(1/x) - (1/y ) = 3,可得:(y-x)/xy=3,得:x+3xy-y=0.2)2x+3xy-2y)/(x-2xy-y)可以进一步分解成:{x+(x+3xy-y)-Y}/{(x+3xy-y)-5xy} 3)将x+3xy-y=0.代入{x+(x+3xy-y)-Y}/{(x+3xy-y)-5xy}中,得:(x+0-y)/(0-5xy)...