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MathNet 2007-part-01 — 187 problems (EN–VI) Question 129

Math Olympiad Vault · MathNet 2007-part-01 — 187 problems (EN–VI)

Question 129

Suppose real number $a$ satisfies $|2x - a| + |3x - 2a| \ge a^2$ for any $x \in \mathbb{R}$. Then $a$ lies exactly in ( ).

(A) $\left[ -\frac{1}{3}, \frac{1}{3} \right]$
(B) $\left[ -\frac{1}{2}, \frac{1}{2} \right]$
(C) $\left[ -\frac{1}{4}, \frac{1}{3} \right]$
(D) $[-3, 3]$