由题意得
XY-X-Y-4=0
即
(X-1)(Y-1)=5
所以有
X-1=5
Y-1=1
或
X-1=1
Y-1=5
或
X-1=-5
Y-1=-1
或
X-1=-1
Y-1=-5
解得：
X=6`````2`````-4`````0
Y=2`````6`````0`````-4