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2019 Math Prize for Girls Problems
9
Math Prize 2019 Problem 9
Math Prize 2019 Problem 9
Source:
October 15, 2019
Math Prize for Girls
Problem Statement
Find the least real number
K
K
K
such that for all real numbers
x
x
x
and
y
y
y
, we have
(
1
+
20
x
2
)
(
1
+
19
y
2
)
≥
K
x
y
(1 + 20 x^2)(1 + 19 y^2) \ge K xy
(
1
+
20
x
2
)
(
1
+
19
y
2
)
≥
K
x
y
.
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