Câu 11:
`ĐK: a < 1`
Để `[a; (a + 1)/2] ⊂ (-∞; -1) ∪ (1; +∞)`
`<=>` \(\left[ \begin{array}{l}\dfrac{a + 1}{2} < -1\\a > 1\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}a + 1 < -2\\a > 1 (l)\end{array} \right.\)
`=> a < -3`
`=> a ∈ (-∞; -3)`
Câu 14:
`a)`
`ĐK: m > -2/3`
`A = [1 - 2m; m + 3]`
`B = [8 - 5m; +∞)`
Để `A ∩ B = ∅`
`<=> m + 3 < 8 - 5m`
`<=> 6m < 5`
`<=> m < 5/6`
`=> -2/3 < m < 5/6`
`=> m ∈ (-2/3; 5/6)`
`b)` Để `A ∪ B = RR`
`<=> m + 1 ≥ -1`
`<=> m ≥ -2`
`=> m ∈ [-2; +∞)`
