Hello 'struggling with GRE',
I will solve the question step by step:
\(20 + \sqrt{80}\)
\(= 20 + \sqrt{16*5}\)
\(= 20 + \sqrt{4^2*5}\)
\(= 20 + 4\sqrt{5}\)
\(= 4*5 + 4\sqrt{5}\)
\(= 4(5 + \sqrt{5})\)
Therefore if you take a root of the above expression what you get is:
\(2\sqrt{(5 + sqrt(5))}\)
So the correct choice is D.
If this helps , let me know with kudos :D
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