Đáp án:
\(m \le - {7 \over 2}\)
Giải thích các bước giải:
\(\eqalign{
& DKXD:\,\,\left\{ \matrix{
x - m > 0 \hfill \cr
2m + 6 - x \ge 0 \hfill \cr} \right. \cr
& \Leftrightarrow \left\{ \matrix{
x > m \hfill \cr
x \le - 2m - 6 \hfill \cr} \right. \cr
& TH1:\,\,m > - 2m - 6 \Leftrightarrow 3m > - 6 \Leftrightarrow m > - 2 \cr
& \Rightarrow D = \emptyset \Rightarrow Loai. \cr
& TH2:\,\,m = - 2m - 6 \Leftrightarrow m = - 2 \cr
& \Leftrightarrow \left\{ \matrix{
x > - 2 \hfill \cr
x \le - 2 \hfill \cr} \right. \Rightarrow D = \emptyset \Rightarrow Loai. \cr
& \Rightarrow Khi\,\,m < - 2\,\,thi\,\,D = \left( {m; - 2m - 6} \right] \cr
& De\,\,ham\,\,so\,\,xac\,\,dinh\,\,tren\,\left( {0;1} \right) \cr
& \Rightarrow \left( {0;1} \right) \subset \left( {m; - 2m - 6} \right] \cr
& \Rightarrow \left\{ \matrix{
m \le 0 \hfill \cr
1 \le - 2m - 6 \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{
m \le 0 \hfill \cr
2m \le - 7 \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{
m \le 0 \hfill \cr
m \le - {7 \over 2} \hfill \cr} \right. \Leftrightarrow m \le - {7 \over 2}\,\,\left( {tm\,\,m < - 2} \right) \cr
& Vay\,\,m \le - {7 \over 2} \cr} \)
