Đáp án:
$\begin{array}{l}
\dfrac{{\sqrt {6 - 2\sqrt 5 } + 2}}{{\sqrt {6 - 2\sqrt 5 } - 2}} = \dfrac{{\sqrt {{{\left( {\sqrt 5 - 1} \right)}^2}} + 2}}{{\sqrt {{{\left( {\sqrt 5 - 1} \right)}^2}} - 2}}\\
= \dfrac{{\sqrt 5 - 1 + 2}}{{\sqrt 5 - 1 - 2}} = \dfrac{{\sqrt 5 + 1}}{{\sqrt 5 - 3}}\\
= \dfrac{{\left( {\sqrt 5 + 1} \right)\left( {\sqrt 5 + 3} \right)}}{{\left( {\sqrt 5 - 3} \right)\left( {\sqrt 5 + 3} \right)}}\\
= \dfrac{{5 + 3\sqrt 5 + \sqrt 5 + 3}}{{5 - 9}}\\
= \dfrac{{8 + 4\sqrt 5 }}{{ - 4}}\\
= - 2 - \sqrt 5
\end{array}$
