若xy=x-y不等于0,则分式1/y-1/x=a.1/xy b.y-x c.1 d.-1

若xy=x-y不等于0,则分式1/y-1/x=a.1/xy b.y-x c.1 d.-1
若xy=x-y不等于0,则分式1/y-1/x=
a.1/xy b.y-x c.1 d.-1

若xy=x-y不等于0,则分式1/y-1/x=a.1/xy b.y-x c.1 d.-1
等于1.
通分：1/Y=x/xy,1/x=y/xy.
所以：1/y-1/x=x-y/xy
因为xy=x-y,
所以：1/y-1/x=1

1/y-1/x=(x-y)/xy=xy/(xy)=1
故答案选c

c