Đáp án:
\(\begin{array}{l}
f\left( x \right) > 0 \to x \in \left( { - 1;0} \right) \cup \left( {1; + \infty } \right)\\
f\left( x \right) < 0 \to x \in \left( { - \infty ; - 1} \right) \cup \left( {0;1} \right)
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
DK:x \ne \pm 1\\
f\left( x \right) = 0\\
\Leftrightarrow x = 0
\end{array}\)
BXD:
x -∞ -1 0 1 +∞
f(x) - // + 0 - // +
\(\begin{array}{l}
KL:f\left( x \right) > 0 \to x \in \left( { - 1;0} \right) \cup \left( {1; + \infty } \right)\\
f\left( x \right) < 0 \to x \in \left( { - \infty ; - 1} \right) \cup \left( {0;1} \right)
\end{array}\)
