\[\left( \sqrt{x^{2} - 12x + 36} \right)^{2} = (4)^{2}\ \]
\[x^{2} - 12x + 36 = 16\]
\[x² - 12x + 20 = 0\]
\[D = 144 - 80 = 64\]
\[x_{1,2} = \frac{12 \pm 8}{2} = 10;2\]
\[(x - 10)(x - 2) = 0\]
\[Ответ:\ 10;2.\]