Question

Answer 1

1<=|x|<=2

=>\(\left[{}\begin{matrix}1< =x< =2\\-2< =x< =-1\end{matrix}\right.\)

=>\(A=\left[1;2\right]\cup\left[-2;-1\right]\)

\(A=\left[-2;-1\right]\cup\left[1;2\right]\)

\(B=\left(-\infty;m-2\right)\cup[m;+\infty)\)

Để A giao B bằng rỗng thì \(\left[{}\begin{matrix}m-2< =-2\\m>2\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}m< =0\\m>2\end{matrix}\right.\)

=>Để A giao B khác rỗng thì \(\left\{{}\begin{matrix}m>0\\m< =2\end{matrix}\right.\Leftrightarrow0< m< =2\)