$m - 3\sqrt{m - 1} = 1$ (ĐK $m \geq 1$)
$\Leftrightarrow 3\sqrt{m - 1} = m - 1$
$\Leftrightarrow 9(m - 1) = m^{2} - 2m + 1 = 0$
$\Leftrightarrow 9m - 9 = m^{2} - 2m + 1 = 0$
$\Leftrightarrow m^{2} - 11m + 10 = 0$
$\Leftrightarrow (m - 1)(m - 10) = 0$
$\Leftrightarrow \left[ \begin{array}{l}m - 1 = 0\\m - 10 = 0\end{array} \right.$
$\Leftrightarrow \left[ \begin{array}{l}m = 1 (TM)\\m = 10 (TM)\end{array} \right.$