\[x^{2} - 64 = 0\]
\[(x - 8)(x + 8) = 0\]
\[x - 8 = 0\ \ \ \ \ \ \ \ x + 8 = 0\]
\[x = 8\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - 8\]
\[Ответ:\ x = \pm 8.\]