DKXD $f(x)$ là $|x-2| - 1 > 0 \iff |x-2| > 1 \iff x - 2 > 1 \vee x-2 < - 1 \iff x > 3 \vee x < 1$
$D_1 = (-\infty, 1) \cup (3, +\infty)$
DKXD $g(x)$ là $m - 2x \geqslant 0$ hay $x \leqslant \dfrac12 m$
$D_2 = (-\infty, \dfrac12 m]$
Muốn $D_2 \subset D_1$ thì $\dfrac12 m < 1$ hay $m < 2$