Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
d,\\
DKXD:\,\,\,\,x \ge 0\\
\sqrt {25x - 30\sqrt x + 9} = 2\\
\Leftrightarrow \sqrt {{{\left( {\sqrt 5 x} \right)}^2} - 2.\sqrt 5 x.3 + {3^2}} = 2\\
\Leftrightarrow \sqrt {{{\left( {\sqrt 5 x - 3} \right)}^2}} = 2\\
\Leftrightarrow \left| {\sqrt 5 x - 3} \right| = 2\\
\Leftrightarrow \left[ \begin{array}{l}
\sqrt 5 x - 3 = 2\\
\sqrt 5 x - 3 = - 2
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
\sqrt 5 x = 5\\
\sqrt 5 x = 1
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
\sqrt x = 1\\
\sqrt x = \dfrac{1}{5}
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x = 1\\
x = \dfrac{1}{{25}}
\end{array} \right.\\
e,\\
DKXD:\,\,\,\,x \ge 0\\
\sqrt {9x} - 5\sqrt x = 6 - 4\sqrt x \\
\Leftrightarrow \sqrt {{3^2}.x} - 5\sqrt x = 6 - 4\sqrt x \\
\Leftrightarrow 3\sqrt x - 5\sqrt x + 4\sqrt x = 6\\
\Leftrightarrow 2\sqrt x = 6\\
\Leftrightarrow \sqrt x = 3\\
\Leftrightarrow x = 9
\end{array}\)
