Câu a: \[\begin{array}{l}
\sqrt {36{x^2} - 24x + 4} = 4\\
\Leftrightarrow \sqrt {{{\left( {6x - 2} \right)}^2}} = 4\\
\Leftrightarrow |6x - 2| = 4\\
\Leftrightarrow \left[ {\begin{array}{*{20}{c}}
{6x - 2 = 4}\\
{6x - 2 = - 4}
\end{array}} \right.\\
\Leftrightarrow \left[ {\begin{array}{*{20}{c}}
{x = 1}\\
{x = \dfrac{{ - 1}}{3}}
\end{array}} \right.
\end{array}\]
Câu b:
\[\begin{array}{l}
\sqrt {16x - 32} - \sqrt {4x - 8} + \sqrt {9x - 18} = 1\\
\Leftrightarrow 4\sqrt {x - 2} - 2\sqrt {x - 2} + 3\sqrt {x - 2} = 1\\
\Leftrightarrow 5\sqrt {x - 2} = 1\\
\Leftrightarrow 25x - 50 = 1\\
\Leftrightarrow x = \dfrac{{51}}{{25}}
\end{array}\]
