已知x分之一减去y分之一等于5,求分式x-3xy-y分之3x+5xy-3y的值

问题描述:

已知x分之一减去y分之一等于5,求分式x-3xy-y分之3x+5xy-3y的值

1/x-1/y=5
(y-x)/xy=5
y-x=5xy
x-y=-5xy
(3x+5xy-3y)/(x-3xy-y)=【3×(-5xy)+5xy】/(-5xy-3xy)
=-10xy/-8xy
=5/4