Phương trình \(\left( {x + \frac{2}{3}} \right)\le...

A

- Hướng dẫn giải

\(\begin{array}{l}
\left( {x + \frac{2}{3}} \right)\left( {x - \frac{1}{2}} \right) = 0\\
 \Leftrightarrow \left[ \begin{array}{l}
x + \frac{2}{3} = 0\\
x - \frac{1}{2} = 0
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x =  - \frac{2}{3}\\
x = \frac{1}{2}
\end{array} \right.
\end{array}\)

Vì x₁ > x₂ nên \({x_1} = \frac{1}{2},{x_2} =  - \frac{2}{3}\)

\(5{x_1} + 8{x_2} = 5.\frac{1}{2} + 8.\left( { - \frac{2}{3}} \right) =  - \frac{{17}}{6}\)