Difference between revisions of "2024 AIME II Problems/Problem 4"

(Created page with "If 69+420=69.42x, what is the value of x?")
 
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If 69+420=69.42x, what is the value of x?
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==Problem==
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Let <math>x,y</math> and <math>z</math> be positive real numbers that satisfy the following system of equations:
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<cmath>\log_2\left({x \over yz}\right) = {1 \over 2}</cmath><cmath>\log_2\left({y \over xz}\right) = {1 \over 3}</cmath><cmath>\log_2\left({z \over xy}\right) = {1 \over 4}</cmath>
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Then the value of <math>\left|\log_2(x^4y^3z^2)\right|</math> is <math>{m \over n}</math> where <math>m</math> and <math>n</math> are relatively prime positive integers. Find <math>m+n</math>.
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==Solution 1==
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Denote <math>\log_2(x) = a</math>, <math>\log_2(y) = b</math>, and <math>\log_2(z) = c</math>.
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Then, we have:
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<math>a-b-c = \frac{1}{2}</math>
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<math>-a+b-c = \frac{1}{3}</math>
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<math>-a-b+c = \frac{1}{4}</math>
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Now, we can solve to get <math>a = \frac{-7}{24}, b = \frac{-9}{24}, c = \frac{-5}{12}</math>. Plugging these values in, we obtain <math>\mid 4a + 3b + 2c \mid = \frac{25}{8} \implies \boxed{033}</math>. ~akliu

Revision as of 20:03, 8 February 2024

Problem

Let $x,y$ and $z$ be positive real numbers that satisfy the following system of equations: \[\log_2\left({x \over yz}\right) = {1 \over 2}\]\[\log_2\left({y \over xz}\right) = {1 \over 3}\]\[\log_2\left({z \over xy}\right) = {1 \over 4}\] Then the value of $\left|\log_2(x^4y^3z^2)\right|$ is ${m \over n}$ where $m$ and $n$ are relatively prime positive integers. Find $m+n$.

Solution 1

Denote $\log_2(x) = a$, $\log_2(y) = b$, and $\log_2(z) = c$.

Then, we have: $a-b-c = \frac{1}{2}$ $-a+b-c = \frac{1}{3}$ $-a-b+c = \frac{1}{4}$

Now, we can solve to get $a = \frac{-7}{24}, b = \frac{-9}{24}, c = \frac{-5}{12}$. Plugging these values in, we obtain $\mid 4a + 3b + 2c \mid = \frac{25}{8} \implies \boxed{033}$. ~akliu