y/x-x/y=3,通分得到(y方-x方)/xy=3,得到y方-x方=3xy,两边同乘以-1,得到x方-y方=xy.
(2x方+3xy-2y方)/(x方-2xy-y方)=[2(x方-y方)+3xy]/(x方-y方-2xy)=-3xy/-5xy=3/5
y/x-x/y=3,通分得到(y方-x方)/xy=3,得到y方-x方=3xy,两边同乘以-1,得到x方-y方=xy.
(2x方+3xy-2y方)/(x方-2xy-y方)=[2(x方-y方)+3xy]/(x方-y方-2xy)=-3xy/-5xy=3/5