Lời giải:Ta có:
\(\begin{array}{*{20}{l}} {\sqrt {\frac{{3 - \sqrt 5 }}{{3 + \sqrt 5 }}} + \sqrt {\frac{{3 + \sqrt 5 }}{{3 - \sqrt 5 }}} }\\ { = \sqrt {\frac{{{{(3 - \sqrt 5 )}^2}}}{{(3 + \sqrt 5 ).(3 - \sqrt 5 )}}} + \sqrt {\frac{{{{(3 + \sqrt 5 )}^2}}}{{(3 + \sqrt 5 ).(3 - \sqrt 5 )}}} }\\ { = \sqrt {\frac{{{{\left( {3 - \sqrt 5 } \right)}^2}}}{{9 - 5}}} + \sqrt {\frac{{{{\left( {3 + \sqrt 5 } \right)}^2}}}{{9 - 5}}} }\\ { = \sqrt {\frac{{{{\left( {3 - \sqrt 5 } \right)}^2}}}{4}} + \sqrt {\frac{{{{\left( {3 + \sqrt 5 } \right)}^2}}}{4}} }\\ { = \frac{{3 - \sqrt 5 }}{2} + \frac{{3 + \sqrt 5 }}{2}}\\ { = \frac{{3 - \sqrt 5 + 3 + \sqrt 5 }}{2} = 3} \end{array}\)
