方程化為（x-4)(y-4)=16
因此左邊每個(gè)因式都是16的因數(shù).
x-4=1,2,4,8,16,
y-4=16,8,4,2,1
即有以下5組正整數(shù)
x=5,6,8,12,20
y=20,12,8,6,5
如果求的是整數(shù)解,那還相應(yīng)有另五組負(fù)整數(shù)
x-4=-1,-2,-4,-8,-16
y-4=-16,-8,-4,-2,-1
x=3,2,0,-4,-12
y=-12,-4,0,2,3