(x+y)(x+y)=625/36
(x+y)^2=625/36
x+y＝±25/6
x-y＝7/6
当x+y＝25/6
x-y＝7/6时
x＝8/3
y＝3/2
xy＝4
当x+y＝-25/6
x-y＝7/6时
x＝-3/2
y＝-8/3
xy＝4
所以
xy＝4