=>(x2-6x-5)(x2-6x+5)=0
=>(x-1)(x-5)(x2-6x+9-14)=0
hay \(x\in\left\{1;5;\sqrt{14}+3;-\sqrt{14}+3\right\}\)
\(\Leftrightarrow\left(x^2-6x\right)^2=25.\\ \Leftrightarrow\left[{}\begin{matrix}x^2-6x=5.\\x^2-6x=-5.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-6x-5=0.\\x^2-6x+5=0.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x=3+\sqrt{14}.\\x=3-\sqrt{14}.\end{matrix}\right.\\\left[{}\begin{matrix}x=5.\\x=1.\end{matrix}\right.\end{matrix}\right.\)
\(\left(x^2-6x\right)^2-25=0\)
\(\Rightarrow\left(x^2-6x\right)^2-5^2=0\)
\(\Rightarrow\left(x^2-6x-5\right)\left(x^2-6x+5\right)=0\)
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