\(\left(a\right):x^2-64=0< =>\left(x-8\right)\left(x+8\right)=0\\ =>\left[{}\begin{matrix}x-8=0\\x+8=0\end{matrix}\right.< =>\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)
\(\left(b\right):4x^2-4x+1=0< =>\left(2x-1\right)^2=0\\ < =>2x-1=0\\ < =>x=\dfrac{1}{2}\)
\(\left(c\right):9-6x+x^2=0< =>\left(3-x\right)^2=0\\ < =>3-x=0\\ < =>x=3\)
a) \(x^2-64=0\)
\(\Leftrightarrow x^2-8^2=0\)
\(\Leftrightarrow\left(x-8\right)\left(x+8\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-8=0\\x+8=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)
b) \(4x^2-4x+1=0\)
\(\Leftrightarrow\left(2x\right)^2-2.2x.1+1=0\)
\(\Leftrightarrow\left(2x-1\right)^2=0\)
\(\Leftrightarrow2x-1=0\) \(\Leftrightarrow x=\dfrac{1}{2}\)
c) \(9-6x+x^2=0\)
\(\Leftrightarrow3^2-2.3.x+x^2=0\)
\(\Leftrightarrow\left(3-x\right)^2=0\)
\(\Leftrightarrow3-x=0\Leftrightarrow x=3\)
