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The number of ordered pairs (x, y) satis...

The number of ordered pairs (x, y) satisfying `4("log"_(2) x^(2))^(2) + 1 = 2 "log"_(2)y " and log"_(2)x^(2) ge "log"_(2) y`, is

A

1

B

2

C

more than 2 but finite

D

infinite

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The correct Answer is:
To solve the problem step by step, we need to analyze the given equation and the conditions provided. ### Step 1: Rewrite the given equation The equation we need to solve is: \[ 4(\log_2 x^2)^2 + 1 = 2 \log_2 y \] ### Step 2: Simplify the logarithmic expressions We can rewrite \(\log_2 x^2\) as \(2 \log_2 x\). Thus, we have: \[ 4(2 \log_2 x)^2 + 1 = 2 \log_2 y \] This simplifies to: \[ 16 (\log_2 x)^2 + 1 = 2 \log_2 y \] ### Step 3: Rearranging the equation Rearranging gives us: \[ 2 \log_2 y = 16 (\log_2 x)^2 + 1 \] Dividing both sides by 2: \[ \log_2 y = 8 (\log_2 x)^2 + \frac{1}{2} \] ### Step 4: Express \(y\) in terms of \(x\) Exponentiating both sides to eliminate the logarithm: \[ y = 2^{8 (\log_2 x)^2 + \frac{1}{2}} \] This can be rewritten as: \[ y = 2^{\frac{1}{2}} \cdot 2^{8 (\log_2 x)^2} = \sqrt{2} \cdot (x^8)^{\log_2 2} = \sqrt{2} \cdot x^8 \] ### Step 5: Analyze the second condition The second condition given is: \[ \log_2 x^2 \geq \log_2 y \] This implies: \[ x^2 \geq y \] ### Step 6: Substitute \(y\) into the inequality Substituting \(y\) from Step 4 into the inequality: \[ x^2 \geq \sqrt{2} \cdot x^8 \] ### Step 7: Rearranging the inequality Rearranging gives us: \[ x^2 - \sqrt{2} x^8 \geq 0 \] Factoring out \(x^2\): \[ x^2 (1 - \sqrt{2} x^6) \geq 0 \] ### Step 8: Finding the critical points The critical points occur when: 1. \(x^2 = 0\) (which gives \(x = 0\), but \(x\) must be positive) 2. \(1 - \sqrt{2} x^6 = 0\) leading to: \[ x^6 = \frac{1}{\sqrt{2}} \] \[ x = \left(\frac{1}{\sqrt{2}}\right)^{\frac{1}{6}} = 2^{-\frac{1}{12}} \] ### Step 9: Determine the intervals The inequality \(x^2 (1 - \sqrt{2} x^6) \geq 0\) holds true when: - \(x^2 \geq 0\) (always true for \(x > 0\)) - \(1 - \sqrt{2} x^6 \geq 0\) which gives: \[ x^6 \leq \frac{1}{\sqrt{2}} \] Thus: \[ x \leq \left(\frac{1}{\sqrt{2}}\right)^{\frac{1}{6}} = 2^{-\frac{1}{12}} \] ### Step 10: Finding the range for \(y\) From the earlier steps, we have: \[ y = \sqrt{2} \cdot x^8 \] Substituting \(x = 2^{-\frac{1}{12}}\): \[ y = \sqrt{2} \cdot \left(2^{-\frac{1}{12}}\right)^8 = \sqrt{2} \cdot 2^{-\frac{2}{3}} = 2^{\frac{1}{2} - \frac{2}{3}} = 2^{-\frac{1}{6}} \] ### Conclusion The ordered pairs \((x, y)\) satisfy the conditions with \(y\) ranging from \(0\) to \(2^{-\frac{1}{6}}\) as \(x\) varies from \(0\) to \(2^{-\frac{1}{12}}\). Since \(y\) can take infinitely many values in the range, the number of ordered pairs \((x, y)\) is infinite. ### Final Answer The number of ordered pairs \((x, y)\) satisfying the conditions is infinite. ---

To solve the problem step by step, we need to analyze the given equation and the conditions provided. ### Step 1: Rewrite the given equation The equation we need to solve is: \[ 4(\log_2 x^2)^2 + 1 = 2 \log_2 y \] ### Step 2: Simplify the logarithmic expressions We can rewrite \(\log_2 x^2\) as \(2 \log_2 x\). Thus, we have: ...
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