Đáp án:
m>0
Giải thích các bước giải:
$$\eqalign{
& y = {{ - \cos x + m} \over {\cos x + m}} \cr
& Dat\,\,t = \cos x \cr
& x \in \left( {0;{\pi \over 2}} \right) \Rightarrow t \in \left( {0;1} \right) \cr
& Ycbt \Leftrightarrow tim\,\,m\,\,de\,\,ham\,\,\,so\,\,y = {{ - t + m} \over {t + m}}\,\,\left( {t \ne - m} \right)\,\,NB/\left( {0;1} \right) \cr
& y' = {{ - 2m} \over {{{\left( {t + m} \right)}^2}}} \cr
& Hs\,\,NB/\left( {0;1} \right) \cr
& \Leftrightarrow \left\{ \matrix{
- 2m < 0 \hfill \cr
- m \notin \left( {0;1} \right) \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{
m > 0 \hfill \cr
\left[ \matrix{
m \ge 0 \hfill \cr
m \le - 1 \hfill \cr} \right. \hfill \cr} \right. \cr
& \Leftrightarrow m > 0 \cr} $$
