What is the value of: \( 6 + \log_{\frac{1}{4}} \left( \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \dots \infty}}}} \right) \)
Step-by-step Solution:
We are given the expression:
\[
6 + \log_{\frac{1}{4}} \left( \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \sqrt{1 - \frac{1}{\sqrt{2}} \dots \infty}}}} \right)
\]
Step 1: Evaluating the Infinite Nested Radical
Consider the infinite nested radical:
\[
x = \sqrt{1 - \frac{1}{\sqrt{2}} x}
\]
Squaring both sides,
\[
x^2 = 1 - \frac{1}{\sqrt{2}} x
\]
Rearrange into a quadratic equation:
\[
x^2 + \frac{1}{\sqrt{2}} x - 1 = 0
\]
Using the quadratic formula, \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \), with \( a = 1 \), \( b = \frac{1}{\sqrt{2}} \), and \( c = -1 \):
\[
x = \frac{-\frac{1}{\sqrt{2}} \pm \sqrt{\left(\frac{1}{\sqrt{2}}\right)^2 + 4}}{2}
\]
\[
x = \frac{-\frac{1}{\sqrt{2}} \pm \sqrt{\frac{1}{2} + 4}}{2}
\]
\[
x = \frac{-\frac{1}{\sqrt{2}} \pm \sqrt{\frac{9}{2}}}{2}
\]
\[
x = \frac{-\frac{1}{\sqrt{2}} \pm \frac{3}{\sqrt{2}}}{2}
\]
\[
x = \frac{-1 + 3}{2\sqrt{2}} \text{ or } x = \frac{-1 - 3}{2\sqrt{2}}
\]
\[
x = \frac{2}{2\sqrt{2}} = \frac{1}{\sqrt{2}}, \quad \text{(choosing the positive root)}
\]
Thus,
\[
x = \frac{1}{\sqrt{2}}
\]
Step 2: Evaluating the Logarithm
We now substitute \( x = \frac{1}{\sqrt{2}} \):
\[
\log_{\frac{1}{4}} \left( \frac{1}{\sqrt{2}} x \right) = \log_{\frac{1}{4}} \left( \frac{1}{\sqrt{2}} \times \frac{1}{\sqrt{2}} \right)
\]
\[
= \log_{\frac{1}{4}} \left( \frac{1}{2} \right)
\]
Since \( \frac{1}{4} = 4^{-1} \), we convert the logarithm:
\[
\log_{\frac{1}{4}} \frac{1}{2} = \frac{\log 1/2}{\log 1/4}
\]
\[
= \frac{\log_4 2^{-1}}{\log_4 4^{-1}}
\]
\[
= \frac{-\log_4 2}{-1} = \log_4 2
\]
Since \( 4 = 2^2 \), we use \( \log_{2^2} 2 = \frac{1}{2} \):
\[
\log_4 2 = \frac{1}{2}
\]
Step 3: Final Calculation
\[
6 + \frac{1}{2} = \frac{13}{2}
\]