Đáp án:
\(\begin{array}{l}
2)x = 0\\
4)x = - \dfrac{{13}}{2}\\
6)x = - \dfrac{1}{6}\\
8)\left[ \begin{array}{l}
x = 3\\
x = \dfrac{1}{2}
\end{array} \right.
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
2){x^3} + 27 - x\left( {{x^2} - 1} \right) - 27 = 0\\
\to {x^3} - {x^3} + x = 0\\
\to x = 0\\
4)3{x^2} + 2x + {x^2} + 2x + 1 - 4{x^2} + 25 = 0\\
\to 4x + 26 = 0\\
\to x = - \dfrac{{13}}{2}\\
6)9\left( {{x^2} + 2x + 1} \right) - 9{x^2} + 4 - 10 = 0\\
\to 9{x^2} + 18x + 9 - 9{x^2} - 6 = 0\\
\to 18x + 3 = 0\\
\to x = - \dfrac{1}{6}\\
8)4x\left( {x - 3} \right) - 2\left( {x - 3} \right) = 0\\
\to \left( {x - 3} \right)\left( {4x - 2} \right) = 0\\
\to \left[ \begin{array}{l}
x - 3 = 0\\
4x - 2 = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 3\\
x = \dfrac{1}{2}
\end{array} \right.
\end{array}\)