\(\left(x-3\right)^2-4=0\)
\(\Leftrightarrow\left(x-3\right)^2=4\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=\sqrt{4}\\x-3=-\sqrt{4}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x-3=2\\x-3=-2\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=1\end{matrix}\right.\)
Vậy ..
\(\left(x-3\right)^2-4=0\)
\(\Leftrightarrow\left(x-3\right)^2-2^2=0\)
\(\Leftrightarrow\left(x-3-2\right)\left(x-3+2\right)=0\)
\(\Leftrightarrow\left(x-5\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=5\end{matrix}\right.\)
Vậy \(x=1\) hoặc \(x=5\)
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