Question

Find the positive square root of 6-√20.

Answer 1

$6 - \sqrt{20} = 6 - 2 \sqrt{5} \\ = (5 + 1) - 2 \sqrt{5} \\ = { \sqrt{5} }^{2} + {1}^{2} - 2 \times \sqrt{5} \times 1 \\ = {( \sqrt{5} - 1)}^{2} \\ therefore \\ \sqrt{(6 - \sqrt{20} )} = \sqrt{5} - 1$