Giải thích các bước giải:
a,
ĐKXĐ: \(\left\{ \begin{array}{l}
x \ge 0\\
\sqrt x - 2 \ne 0\\
\sqrt x + 2 \ne 0\\
\frac{{2x}}{{x - 4}} \ne 0
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x > 0\\
x \ne 4
\end{array} \right.\)
b,
\(\begin{array}{l}
P = \left( {\frac{1}{{\sqrt x - 2}} + \frac{1}{{\sqrt x + 2}}} \right):\frac{{2x}}{{x - 4}}\\
= \frac{{\left( {\sqrt x + 2} \right) + \left( {\sqrt x - 2} \right)}}{{\left( {\sqrt x + 2} \right)\left( {\sqrt x - 2} \right)}}:\frac{{2x}}{{x - 4}}\\
= \frac{{2\sqrt x }}{{x - 4}}.\frac{{x - 4}}{{2x}}\\
= \frac{{\sqrt x }}{x}\\
= \frac{1}{{\sqrt x }}\\
c,\\
P < 1 \Leftrightarrow \frac{1}{{\sqrt x }} < 1 \Leftrightarrow \sqrt x > 1 \Leftrightarrow \left\{ \begin{array}{l}
x > 1\\
x \ne 4
\end{array} \right.
\end{array}\)
