Đáp án:
$\begin{array}{l}
a)A = \sqrt {{{\left( {\sqrt 3 - 2} \right)}^2}} - \sqrt {7 + 4\sqrt 3 } + \sqrt {27} - \dfrac{2}{{\sqrt 3 - 1}}\\
= 2 - \sqrt 3 - \sqrt {{{\left( {2 + \sqrt 3 } \right)}^2}} + 3\sqrt 3 - \dfrac{{2\left( {\sqrt 3 + 1} \right)}}{{3 - 1}}\\
= 2 - \sqrt 3 - 2 - \sqrt 3 + 3\sqrt 3 - \left( {\sqrt 3 + 1} \right)\\
= \sqrt 3 - \sqrt 3 - 1\\
= - 1\\
b)B = \sqrt {\dfrac{{\sqrt 5 + 2}}{{\sqrt 5 - 2}}} - \sqrt {24 - 8\sqrt 5 } \\
= \sqrt {\dfrac{{{{\left( {\sqrt 5 + 2} \right)}^2}}}{{5 - {2^2}}}} - \sqrt {20 - 2.2\sqrt 5 .2 + 4} \\
= \sqrt {{{\left( {\sqrt 5 + 2} \right)}^2}} - \sqrt {{{\left( {2\sqrt 5 - 2} \right)}^2}} \\
= \sqrt 5 + 2 - \left( {2\sqrt 5 - 2} \right)\\
= 4 - \sqrt 5 \\
c)C = \dfrac{{5\sqrt 2 - 2\sqrt 5 }}{{\sqrt 5 - \sqrt 2 }} - \dfrac{1}{{\sqrt {10} + 3}}\\
= \dfrac{{\sqrt {10} \left( {\sqrt 5 - \sqrt 2 } \right)}}{{\sqrt 5 - \sqrt 2 }} - \dfrac{{\sqrt {10} - 3}}{{10 - {3^2}}}\\
= \sqrt {10} - \left( {\sqrt {10} - 3} \right)\\
= 3
\end{array}$
