Đáp án:\(\left\{ \begin{array}{l}
x = 1\\
x = 5\\
x = 3\\
x = 7
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
({x^2} - 6x + 8)({x^2} - 10x + 18) + 12x - 39 = 0\\
\Leftrightarrow ({x^2} - 6x + 5)({x^2} - 10x + 9) + 3({x^2} - 10x + 9) + 9({x^2} - 6x + 5) + 27 + 12x - 39 = 0\\
\Leftrightarrow {(x - 1)^2}(x - 5)(x - 9) + 12(x - 1)(x - 5) = 0\\
\Leftrightarrow (x - 1)(x - 5){\rm{[}}(x - 1)(x - 9) + 12] = 0\\
\Leftrightarrow (x - 1)(x - 5)(x - 3)(x - 7) = 0\\
\Leftrightarrow \left\{ \begin{array}{l}
x = 1\\
x = 5\\
x = 3\\
x = 7
\end{array} \right.
\end{array}\)
