\[\begin{array}{*{20}{l}}
\begin{array}{l}
1.{\rm{ }}{\left( {x{\rm{ }}--{\rm{ }}4} \right)^2}{\rm{ }} - {\rm{ }}36{\rm{ }} = {\rm{ }}0\\
= > {\left( {x - 4} \right)^2} = 36\\
= > \left[ \begin{array}{l}
x - 4 = 6\\
x - 4 = - 6
\end{array} \right.\\
= > \left[ \begin{array}{l}
x = 6 + 4\\
x = - 6 + 4
\end{array} \right.\\
= > \left[ \begin{array}{l}
x = 10\\
x = - 2
\end{array} \right.\\
vay:S = \{ - 2;10\}
\end{array}\\
\begin{array}{l}
2.{\rm{ }}{\left( {x{\rm{ }} + {\rm{ }}8} \right)^2}{\rm{ }} = {\rm{ }}121\\
= > \left[ \begin{array}{l}
x + 8 = 11\\
x + 8 = - 11
\end{array} \right.\\
= > \left[ \begin{array}{l}
x = 11 - 8\\
x = - 11 - 8
\end{array} \right.\\
= > \left[ \begin{array}{l}
x = 3\\
x = - 19
\end{array} \right.\\
vay:S = \{ 3; - 19\}
\end{array}\\
\begin{array}{l}
3.{\rm{ }}{x^2}{\rm{ }} + {\rm{ }}8x{\rm{ }} + {\rm{ }}16{\rm{ }} = {\rm{ }}0\\
= > {x^2} + 2.4x + {4^2} = 0\\
= > {\left( {x + 4} \right)^{}} = 0\\
= > x + 4 = 0\\
= > x = - 4\\
vay:x = - 4
\end{array}
\end{array}\]

4. chưa rõ đề