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1993年度全国高中数学竞赛有一这样一个题目:实数x、y满足4x~2-5xy+4y~2=5,设s=x~2+y~2,则1/S_(max)+1/S_(min)的值为______.本文给出它的两个仅用到初中知识的解法。
In the 1993 National High School Mathematics Competition, there was such a problem: real numbers x and y satisfy 4x~2-5xy+4y~2=5, and s=x~2+y~2, then 1/S_(max)+1/S_. The value of (min) is ______. This paper gives two solutions that only use junior high school knowledge.