x-y=1 证明x2+y2+1/x2+1/y2大于等于17/2
设x=2,则y=1,
x2+y2+1/x2+1/y2
=2*2+1*1+1/(2*2)+1/(1*1)
=4+1+1/4+1
=6+1/4
=6.25
x-y=1 ,当设x=2,则y=1；；x2+y2+1/x2+1/y2大于等于17/2是不成立的；
所以题目错误.