Tìm x, biết:a) (frac{2}{3}x({x^2} - 4) = 0)b) 2x2 – x – 6 = 0

* Hướng dẫn giải

a/ 3x(x² – 4) = 0

 <=> 3x(x – 2)(x + 2) = 0

\( \Leftrightarrow \left[ \begin{array}{l}
3x = 0\\
x - 2 = 0\\
x + 2 = 0
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x = 0\\
x = 2\\
x =  - 2
\end{array} \right.\)

b/ 

2x² – x – 6 = 0

<=> 2x(x – 2) + (3(x – 2) = 0

<=> (x – 2)(2x + 3) = 0

\( \Leftrightarrow \left[ \begin{array}{l}
x - 2 = 0\\
2x + 3 = 0
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x = 2\\
x =  - \frac{3}{2}
\end{array} \right.\)