\[\sqrt{x^{2}} = 8 - x\]
\[|x| = 8 - x\]
\[x = 8 - x,\ \ x = - 8 + x\]
\[2x = 8\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0 = - 8\]
\[x = 4\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ нет\ решения.\]
\[Ответ:x = 4.\]