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