Question

Tìm m để B\A=B

\(A=\left\{x\in R,\left|mx-3\right|=mx-3\right\},B=\left\{xthuocR,x^2-4=0\right\}\)

Answer 1

\(\dfrac{-3}{2}\le m\le\dfrac{3}{2}phaikhongvay?\)

Answer 2

\(B=\left\{x\in R|x^2-4=0\right\}=\left\{2;-2\right\}\)

Điều kiện $B\setminus A=B$ nếu $B\cap A=\varnothing$

$\mathrm{\backslash (\backslash Rightarrow\; A=\backslash varnothing\backslash Rightarrow\; mx-3<\; 0\backslash Leftrightarrow\; mx<\; 3\backslash )}$

Với x = 2 ta có: 2m<3 => \(m< \frac{3}{2}\)

Với x = -2 ta có: -2m < 3 => \(m>-\frac{3}{2}\)

=> \(-\frac{3}{2}< m< \frac{3}{2}\)