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Bunuel

Can you please explain the first part of your approach?

I donot get it how you go from the first step to the second and then third step. What did you do between step 1 and step 2 in particular?


Thanks in advance!
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Bunuel

Can you please explain the first part of your approach?

I donot get it how you go from the first step to the second and then third step. What did you do between step 1 and step 2 in particular?


Thanks in advance!

Here \(\sqrt{\frac{\sqrt{2}}{2}}\), we rationalize the fraction under the outer square root by multiplying both the numerator and the denominator by \(\sqrt{2}\) to get:

\(\sqrt{\frac{\sqrt{2} * \sqrt{2}}{2 * \sqrt{2}}} = \sqrt{\frac{2}{2\sqrt{2}}} = \sqrt{\frac{1}{\sqrt{2}}}\).

Next, \(\sqrt{2} = 2^{\frac{1}{2}}\), so we have:

\(\sqrt{\frac{1}{2^{\frac{1}{2}}}}= \sqrt{(\frac{1}{2})^{\frac{1}{2}}} \).
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How did you decide to take the expression to the 4th power, then back to the 1/4 power? Why not any value other than 4?
Bunuel
Official Solution:

If \(x^x=\sqrt{\frac{\sqrt{2}}{2}}\), which of the following could be a value of \(x\)?

A. \(\frac{1}{16}\)
B. \(\frac{1}{4}\)
C. \(\frac{1}{\sqrt{2}}\)
D. \(\frac{1}{2}\)
E. \(\sqrt{2}\)


We need to simplify the expression on the right-hand side of the equation so that it can be written in terms of the same base and exponent as \(x^x\).

\(\sqrt{\frac{\sqrt{2}}{2}}=\)

\(=\sqrt{\frac{1}{\sqrt{2}}}=\)

\(=\sqrt{(\frac{1}{2})^{\frac{1}{2}}}=\)

\(=(\frac{1}{2})^{\frac{1}{4}}=\)

Take to the above expression the fourth power and apply exponentiation to the base, \(\frac{1}{2}\):

\(=((\frac{1}{2})^{\frac{1}{4}})^4=\)

\(=((\frac{1}{2})^4)^{\frac{1}{4}}=\)

\(=(\frac{1}{16})^{\frac{1}{4}}\)

Now, to compensate the previous operation, take the fourth root, but this time apply exponentiation to the exponent, \(\frac{1}{4}\):

\(=((\frac{1}{16})^{\frac{1}{4}})^{\frac{1}{4}}=\)

\(=(\frac{1}{16})^{\frac{1}{16}}\)

Therefor, \(x=\frac{1}{16}\)

Else, after obtaining the expression \(x^x=(\frac{1}{2})^{\frac{1}{4}}\), we can substitute each of the given options for \(x\) to determine which one satisfies the equation.

Option A is a valid solution, as \((\frac{1}{16})^{(\frac{1}{16})}=((\frac{1}{16})^{(\frac{1}{4})})^{(\frac{1}{4})}=(\frac{1}{2})^{\frac{1}{4}}\)


Answer: A
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How did you decide to take the expression to the 4th power, then back to the 1/4 power? Why not any value other than 4?

The fourth power is chosen because it simplifies the expression to a base that matches the form of x^x. Raising to the fourth power and then taking the fourth root allows us to match the exponents and simplify the expression in a way that aligns with the given equation.

For alternative solutions and logic check this thread: https://gmatclub.com/forum/if-x-x-2-1-2 ... 98882.html
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