Đáp án: 

• \(
\overrightarrow{a}, \overrightarrow{b}, \overrightarrow{c} \text{ đồng phẳng} \Leftrightarrow [\overrightarrow{a}, \overrightarrow{b}] .\overrightarrow{c} = 0
\)

\(\begin{cases}
\overrightarrow{a} = (1, -1, 1)\\
\overrightarrow{b} = (0, 1, 2)
\end{cases}
\Rightarrow [\overrightarrow{a}, \overrightarrow{b}] = (-3, -2, 1)\)

•  \([\overrightarrow{a}, \overrightarrow{b}]. \overrightarrow{c} =-12 - 4 + m = 0 \Rightarrow m = 16\)