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National and Regional Contests
Ukraine Contests
Official Ukraine Selection Cycle
Ukraine National Mathematical Olympiad
2021 Ukraine National Mathematical Olympiad
10.3
10.3
Part of
2021 Ukraine National Mathematical Olympiad
Problems
(1)
sum (a^2+b^2)/(a+b) >= (a+b+c)+ (a-c)^2/(a+b+c) for a>= b>= c >0
Source: 2021 Ukraine NMO 10.3
4/2/2021
For arbitrary positive reals
a
≥
b
≥
c
a\ge b \ge c
a
≥
b
≥
c
prove the inequality:
a
2
+
b
2
a
+
b
+
a
2
+
c
2
a
+
c
+
c
2
+
b
2
c
+
b
≥
(
a
+
b
+
c
)
+
(
a
−
c
)
2
a
+
b
+
c
\frac{a^2+b^2}{a+b}+\frac{a^2+c^2}{a+c}+\frac{c^2+b^2}{c+b}\ge (a+b+c)+ \frac{(a-c)^2}{a+b+c}
a
+
b
a
2
+
b
2
+
a
+
c
a
2
+
c
2
+
c
+
b
c
2
+
b
2
≥
(
a
+
b
+
c
)
+
a
+
b
+
c
(
a
−
c
)
2
(Anton Trygub)
algebra
inequalities