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Solve for x, y , z. log2 x + log4 y ...

Solve for `x, y , z`.
`log_2 x + log_4 y + log_4 z =2`
`log_3 y + log_9 z + log_9 x =2`
`log_4 z + log_16 x + log_16 y =2`

A

`(175)/(12)`

B

`(349)/(24)`

C

`(353)/(24)`

D

`(112)/(3)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the equations given in the problem, we will follow a systematic approach using logarithmic properties. ### Given Equations: 1. \( \log_2 x + \log_4 y + \log_4 z = 2 \) 2. \( \log_3 y + \log_9 z + \log_9 x = 2 \) 3. \( \log_4 z + \log_{16} x + \log_{16} y = 2 \) ### Step 1: Simplifying the First Equation We start with the first equation: \[ \log_2 x + \log_4 y + \log_4 z = 2 \] We can convert the logarithms with base 4 to base 2: \[ \log_4 y = \frac{1}{2} \log_2 y \quad \text{and} \quad \log_4 z = \frac{1}{2} \log_2 z \] Substituting these into the equation, we get: \[ \log_2 x + \frac{1}{2} \log_2 y + \frac{1}{2} \log_2 z = 2 \] Multiplying the entire equation by 2 to eliminate the fractions: \[ 2 \log_2 x + \log_2 y + \log_2 z = 4 \] Using the property of logarithms that states \( \log_a b + \log_a c = \log_a (bc) \): \[ \log_2 (x^2) + \log_2 (y) + \log_2 (z) = 4 \] This simplifies to: \[ \log_2 (x^2 y z) = 4 \] Exponentiating both sides gives: \[ x^2 y z = 16 \quad \text{(Equation 1)} \] ### Step 2: Simplifying the Second Equation Now we move to the second equation: \[ \log_3 y + \log_9 z + \log_9 x = 2 \] Converting the logarithms with base 9 to base 3: \[ \log_9 z = \frac{1}{2} \log_3 z \quad \text{and} \quad \log_9 x = \frac{1}{2} \log_3 x \] Substituting these into the equation gives: \[ \log_3 y + \frac{1}{2} \log_3 z + \frac{1}{2} \log_3 x = 2 \] Multiplying the entire equation by 2: \[ 2 \log_3 y + \log_3 z + \log_3 x = 4 \] This simplifies to: \[ \log_3 (y^2) + \log_3 (z) + \log_3 (x) = 4 \] Thus: \[ \log_3 (y^2 x z) = 4 \] Exponentiating both sides gives: \[ y^2 x z = 81 \quad \text{(Equation 2)} \] ### Step 3: Simplifying the Third Equation Now we simplify the third equation: \[ \log_4 z + \log_{16} x + \log_{16} y = 2 \] Converting the logarithms with base 16 to base 4: \[ \log_{16} x = \frac{1}{2} \log_4 x \quad \text{and} \quad \log_{16} y = \frac{1}{2} \log_4 y \] Substituting gives: \[ \log_4 z + \frac{1}{2} \log_4 x + \frac{1}{2} \log_4 y = 2 \] Multiplying the entire equation by 2: \[ 2 \log_4 z + \log_4 x + \log_4 y = 4 \] This simplifies to: \[ \log_4 (z^2) + \log_4 (x) + \log_4 (y) = 4 \] Thus: \[ \log_4 (z^2 x y) = 4 \] Exponentiating both sides gives: \[ z^2 x y = 256 \quad \text{(Equation 3)} \] ### Step 4: Solving the System of Equations Now we have three equations: 1. \( x^2 y z = 16 \) 2. \( y^2 x z = 81 \) 3. \( z^2 x y = 256 \) We can express \( z \) from Equation 1: \[ z = \frac{16}{x^2 y} \] Substituting \( z \) into Equation 2: \[ y^2 x \left(\frac{16}{x^2 y}\right) = 81 \] This simplifies to: \[ \frac{16y}{x} = 81 \implies y = \frac{81x}{16} \] Now substituting \( y \) back into the expression for \( z \): \[ z = \frac{16}{x^2 \left(\frac{81x}{16}\right)} = \frac{256}{81x^3} \] ### Step 5: Substitute into Equation 3 Now substitute \( y \) and \( z \) into Equation 3: \[ \left(\frac{256}{81x^3}\right)^2 x \left(\frac{81x}{16}\right) = 256 \] This simplifies to: \[ \frac{65536}{6561 x^6} \cdot x \cdot \frac{81x}{16} = 256 \] After solving this equation, we find: \[ x = \frac{2}{3} \] ### Step 6: Finding \( y \) and \( z \) Now substituting \( x \) back into the expressions for \( y \) and \( z \): \[ y = \frac{81 \cdot \frac{2}{3}}{16} = \frac{27}{8} \] \[ z = \frac{256}{81 \cdot \left(\frac{2}{3}\right)^3} = \frac{32}{3} \] ### Final Values Thus, the values of \( x, y, z \) are: \[ x = \frac{2}{3}, \quad y = \frac{27}{8}, \quad z = \frac{32}{3} \]
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