Đáp án:
$\begin{array}{l}
a)A = \sqrt {3 - 2\sqrt 2 } - \sqrt {3 + 2\sqrt 2 } \\
= \sqrt {{{\left( {\sqrt 2 - 1} \right)}^2}} - \sqrt {{{\left( {\sqrt 2 + 1} \right)}^2}} \\
= \sqrt 2 - 1 - \left( {\sqrt 2 + 1} \right)\\
= - 2\\
b)B = \sqrt {14 - 5\sqrt 3 } + \sqrt {14 + 5\sqrt 3 } \\
= \dfrac{1}{{\sqrt 2 }}\left( {\sqrt {28 - 2.5\sqrt 3 } + \sqrt {28 + 2.5\sqrt 3 } } \right)\\
= \dfrac{1}{{\sqrt 2 }}.\left( {\sqrt {{{\left( {5 - \sqrt 3 } \right)}^2}} + \sqrt {{{\left( {5 + \sqrt 3 } \right)}^2}} } \right)\\
= \dfrac{1}{{\sqrt 2 }}.\left( {5 - \sqrt 3 + 5 + \sqrt 3 } \right)\\
= \dfrac{1}{{\sqrt 2 }}.2.5\\
= 5\sqrt 2 \\
c)C = \sqrt {{{37}^2} - {{35}^2}} = \sqrt {\left( {37 - 35} \right).\left( {37 + 35} \right)} \\
= \sqrt {2.72} \\
= \sqrt {4.36} \\
= 2.6 = 12\\
d)D = \sqrt {{{65}^2} - {{63}^2}} \\
= \sqrt {\left( {65 - 63} \right)\left( {65 + 63} \right)} \\
= \sqrt {2.128} \\
= \sqrt {256} \\
= 16
\end{array}$
