\[x² - 49 = 0\]
\[(x - 7)(x + 7) = 0\]
\[x - 7 = 0\ \ \ \ \ \ \ x + 7 = 0\]
\[x = 7\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - 7\]
\[Ответ:x = \pm 7.\]