Giải thích các bước giải:
1. Xét
\(\left[ \begin{array}{l}
4{x^2} - 1 = 0\\
- 8{x^2} + x - 3 < 0\forall x \in R\\
2x + 9 = 0
\end{array} \right. \to \left[ \begin{array}{l}
x = \pm \frac{1}{2}\\
x = - \frac{9}{2}
\end{array} \right.\)
BXD:
x -∞ -9/2 -1/2 1/2 +∞
f(x) + 0 - 0 + 0 -
\(\begin{array}{l}
2.ĐK:4{x^2} + x - 3 \ne 0 \to x \ne \left\{ { - 1;\frac{3}{4}} \right\}\\
Xét:\left[ \begin{array}{l}
3{x^2} - x = 0\\
3 - {x^2} = 0
\end{array} \right. \to \left[ \begin{array}{l}
x = 0\\
x = \frac{1}{3}\\
x = \pm \sqrt 3
\end{array} \right.
\end{array}\)
BXD:
x -∞ -√3 -1 0 1/3 3/4 √3 +∞
f(x) - 0 + // - 0 + 0 - // + 0 -
