Question

81,32,,64,?
$\sqrt{5. \sqrt{5. \sqrt{5} } }$

Answer 1

$let \: \sqrt{5 \sqrt{5 \sqrt{5} } } = x \: = = > (1) \\ now. \: squaring \: both \: the \: sides \\ 5 \sqrt{5 \sqrt{5 \sqrt{5} } } = {x}^{2} \\ 5 \times x = {x}^{2} \: = = > from(1) \\ therefore...... \: \: \: \\ x = 5$