Maths Olympiad Prep

Track / Stage 4 / 122 of 340 #382 of 1964

Problem 382

AMC 12 late, AIME early
Algebra Difficulty 4.7 Find the answer

log⁡3log⁡x2log⁡x2x4>0\log _{3} \log _{x^{2}} \log _{x^{2}} x^{4}>0.

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

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Official solution

## Solution.

The given inequality is equivalent to the inequality log⁡x2log⁡x2(x2)2>1⇔\log _{x^{2}} \log _{x^{2}}\left(x^{2}\right)^{2}>1 \Leftrightarrow ⇔log⁡x22log⁡x2x2>1,log⁡x22>1⇔\Leftrightarrow \log _{x^{2}} 2 \log _{x^{2}} x^{2}>1, \log _{x^{2}} 2>1 \Leftrightarrow

!

Answer: x∈(−2;−1)∪(1;2)x \in(-\sqrt{2} ;-1) \cup(1 ; \sqrt{2}).

Source: NuminaMath-1.5, licensed Apache-2.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.