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National High School Mathematics League
1993 National High School Mathematics League
8
Max and Min
Max and Min
Source: 1993 National High School Mathematics League, Exam One, Problem 8
February 27, 2020
Problem Statement
Real number
x
,
y
x,y
x
,
y
satisfy that
4
x
2
−
5
x
y
+
4
y
2
=
5
,
S
=
x
2
+
y
2
4x^2-5xy+4y^2=5,S=x^2+y^2
4
x
2
−
5
x
y
+
4
y
2
=
5
,
S
=
x
2
+
y
2
, then
1
S
max
+
1
S
min
=
\frac{1}{S_\text{max}}+\frac{1}{S_\text{min}}=
S
max
1
+
S
min
1
=
________.
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