Question

6
$6 \sqrt{1 + 2 \sqrt{21} }$
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Answer 1

Answer:

$6 \sqrt{1 + 2 \sqrt{21} } \\ \\ = \sqrt{36 + 72 \sqrt{21} } \\ \\ = \sqrt{36+ \sqrt{72\times 72 \times 21} } \\ \\ \\ = \sqrt{36 + \sqrt{108864} }$