由整体思想十字相乘得：
[(x-y)+1][(x-y)-3]=0
(x-y+1)(x-y-3)=0
x-y+1=0或x-y-3=0
x=y-1或x=y+3
列方程组：
{x=y-1 或{x=y+3
x²-y²=1 x²-y²=1
{y=0 或{y=-4/3
x=-1 x=5/3