Cho P(x) = `x(3x - 1) - 5(3x - 1)`
Mà `P(x) =0`
=> `x(3x - 1) - 5(3x - 1)` = 0
` <=> (x - 5)(3x - 1) ` = 0
<=> \(\left[ \begin{array}{l}x-5 = 0\\3x - 1 =0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x = 5 \\3x = 1\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=5\\x=\frac{1}{3}\end{array} \right.\)
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