\(\left(x-3\right)^2=16\)
\(\Rightarrow\left[{}\begin{matrix}x-3=16\\x-3=-16\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=19\\x=-13\end{matrix}\right.\)
Vậy: \(x\in\left\{19;-13\right\}\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=4\\x-3=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-1\end{matrix}\right.\)
\(\left(x-3\right)^2=16\\ \Rightarrow\left[{}\begin{matrix}x-3=-4\\x-3=4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=-1\\x=7\end{matrix}\right.\)