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MathNet 2016-part-07 — 182 problems (EN–VI) Question 9

Math Olympiad Vault · MathNet 2016-part-07 — 182 problems (EN–VI)

Question 9

For positive numbers $a, b, c$ prove the inequality :
$$
\sqrt{a^2 + bc} + \sqrt{b^2 + ca} + \sqrt{c^2 + ab} \ge \sqrt{ab + bc} + \sqrt{bc + ca} + \sqrt{ca + ab}.
$$