初二已知(1/x)
已知(1/x)-(1/y)=2,求(2x+3xy-2y)/(x-2xy-y)
(1/x)-(1/y)=2 (y-x)/xy=2 [通分] y-x=2xy (2x+3xy-2y)/(x-2xy-y) =[2(x-y)+3xy]/[(x-y)-2xy] =(-4xy+3xy)/(-2xy-2xy) =-xy/-4xy =1/4