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5.
2023 Polish Junior Math Olympiad Round 1 P5
2023 Polish Junior Math Olympiad Round 1 P5
Source:
May 21, 2023
inequalities
algebra
Problem Statement
Positive numbers
a
a
a
,
b
b
b
,
c
c
c
satisfy the inequalities a + b \geq ab, b + c \geq bc, \text{and} c+ a \geq ca. Prove that
a
+
b
+
c
≥
3
4
a
b
c
\displaystyle a + b + c \geq \frac34abc
a
+
b
+
c
≥
4
3
ab
c
.
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