Maths Olympiad Prep

Track / Stage 4 / 86 of 340 #346 of 1964

Problem 346

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

9.195. log3logx2logx2x4>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.

Official solution

## Solution.

The given inequality is equivalent to the inequality logx2logx2(x2)2>1\log _{x^{2}} \log _{x^{2}}\left(x^{2}\right)^{2}>1 \Leftrightarrow logx22logx2x2>1,logx22>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 and solution reproduced as published; topic, difficulty and ordering added by this site.