2024 AMC 12B Problems/Problem 8: Difference between revisions
Kafuu chino (talk | contribs) Created page with "==Problem== What value of <math>x</math> satisfies <cmath>\frac{\log_2x \cdot \log_3x}{\log_2x+\log_3x}=2?</cmath> <math>\textbf{(A) } 25 \qquad\textbf{(B) } 32 \qquad\textbf..." |
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\end{align*} | \end{align*} | ||
so <math>\boxed{\textbf{(C) }36}</math> | so <math>\boxed{\textbf{(C) }36}</math> | ||
==See also== | |||
{{AMC12 box|year=2024|ab=B|num-b=7|num-a=9}} | |||
{{MAA Notice}} | |||
Revision as of 00:42, 14 November 2024
Problem
What value of 
satisfies
![\[\frac{\log_2x \cdot \log_3x}{\log_2x+\log_3x}=2?\]](http://latex.artofproblemsolving.com/a/d/6/ad6c3a949ac3db0de93e322df80e07a3a51e8a91.png)
Solution 1
We have
\begin{align*}
&\log_2x\cdot\log_3x=2(\log_2x+\log_3x) \\
&1=\frac{2(\log_2x+\log_3x)}{\log_2x\cdot\log_3x} \\
&1=2(\frac{1}{\log_3x}+\frac{1}{\log_2x}) \\
&1=2(\log_x3+\log_x2) \\
&\log_x6=\frac{1}{2} \\
&x^{\frac{1}{2}}=6 \\
&x=36
\end{align*}
so 
See also
| 2024 AMC 12B (Problems • Answer Key • Resources) | |
| Preceded by Problem 7 |
Followed by Problem 9 |
| 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | |
| All AMC 12 Problems and Solutions | |
These problems are copyrighted © by the Mathematical Association of America. 
