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MathNet 2019-part-06 — 184 problems (EN–VI) Question 14

Math Olympiad Vault · MathNet 2019-part-06 — 184 problems (EN–VI)

Question 14

Prove the inequality for non-negative $a, b, c$
$$
a \sqrt{3 a^{2}+6 b^{2}}+b \sqrt{3 b^{2}+6 c^{2}}+c \sqrt{3 c^{2}+6 a^{2}} \geq (a+b+c)^{2}.
$$