Question

The six is in the dent in the square root sign and 128 is under it

Answer 1

remember
$\sqrt[n]{x^m} =x^ \frac{m}{n}$

so
128=2^7
$\sqrt[6]{2^7} =2^ \frac{7}{6}$=$(2^ \frac{6}{6})(2^ \frac{1}{6})=2 \sqrt[6]{2}$