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National and Regional Contests
Japan Contests
Japan MO Finals
1997 Japan MO Finals
2
Japan 1997 inequality
Japan 1997 inequality
Source: Japan MO 1997, problem #2
July 27, 2003
inequalities
calculus
AMC
three variable inequality
Hi
Problem Statement
Prove that
(
b
+
c
−
a
)
2
(
b
+
c
)
2
+
a
2
+
(
c
+
a
−
b
)
2
(
c
+
a
)
2
+
b
2
+
(
a
+
b
−
c
)
2
(
a
+
b
)
2
+
c
2
≥
3
5
\frac{\left(b+c-a\right)^{2}}{\left(b+c\right)^{2}+a^{2}}+\frac{\left(c+a-b\right)^{2}}{\left(c+a\right)^{2}+b^{2}}+\frac{\left(a+b-c\right)^{2}}{\left(a+b\right)^{2}+c^{2}}\geq\frac35
(
b
+
c
)
2
+
a
2
(
b
+
c
−
a
)
2
+
(
c
+
a
)
2
+
b
2
(
c
+
a
−
b
)
2
+
(
a
+
b
)
2
+
c
2
(
a
+
b
−
c
)
2
≥
5
3
for any positive real numbers
a
a
a
,
b
b
b
,
c
c
c
.
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