Đáp án:
a. \( - \dfrac{{\sqrt 6 }}{3}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\dfrac{{2.2\sqrt 2 - 2\sqrt 3 }}{{3\sqrt 2 - 4\sqrt 3 }} = \dfrac{{2\left( {2\sqrt 2 - \sqrt 3 } \right)}}{{\sqrt 6 \left( {\sqrt 3 - 2\sqrt 2 } \right)}}\\
= - \dfrac{2}{{\sqrt 6 }} = - \dfrac{{\sqrt 6 }}{3}\\
b.\dfrac{{\sqrt 3 \left( {\sqrt 3 + 2} \right)}}{{\sqrt 3 }} + \dfrac{{\sqrt 2 \left( {\sqrt 2 + 1} \right)}}{{\sqrt 2 + 1}}\\
= \sqrt 3 + 2 + \sqrt 2 \\
c.\dfrac{{{{\left( {x - \sqrt 2 } \right)}^2}}}{{\left( {x - \sqrt 2 } \right)\left( {x + \sqrt 2 } \right)}}\\
= \dfrac{{x - \sqrt 2 }}{{x + \sqrt 2 }}\\
d.\dfrac{{\sqrt x + 5}}{{x + 2\sqrt 5 .\sqrt x + 5}}\\
= \dfrac{{\sqrt x + 5}}{{{{\left( {\sqrt x + 5} \right)}^2}}} = \dfrac{1}{{\sqrt x + 5}}
\end{array}\)
