Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
a,\\
\left\{ \begin{array}{l}
x \in R\\
\left| x \right| < 1
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x \in R\\
- 1 < x < 1
\end{array} \right.\\
\Rightarrow A = \left( { - 1;1} \right)\\
b,\\
\left\{ \begin{array}{l}
x \in R\\
\left| x \right| \le 1
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x \in R\\
- 1 \le x \le 1
\end{array} \right.\\
\Rightarrow B = \left[ { - 1;1} \right]\\
c,\\
\left\{ \begin{array}{l}
x \in R\\
\left| {x - 1} \right| \ge 2
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x \in R\\
\left[ \begin{array}{l}
x - 1 \ge 2\\
x - 1 \le - 2
\end{array} \right.
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x \in R\\
\left[ \begin{array}{l}
x \ge 3\\
x \le - 1
\end{array} \right.
\end{array} \right.\\
\Rightarrow C = \left( { - \infty ; - 1} \right] \cup \left[ {3; + \infty } \right)
\end{array}\)
