`text{Bài 1}`
`D = (-1; +infty)`
`|x - 2| > x + 1`
`-> x^2 - 4x + 4 > x^2 + 2x + 1`
`-> 6x - 3 < 0`
`-> x < 1/2`
`-> x in (-infty; 1/2)`
`text{Bài 2}`
`D = (-1/2; +infty)`
`|x^2 + x - 16| <= 4x + 2`
`-> x^2 + x - 16 <= 16x^2 + 16x + 4`
`-> 15x^2 + 15x + 20 >= 0 \(lđ)`
`-> S = RR`
`text{Bài 3}`
`D = [-3/2; +infty)`
`sqrt{2x^2 - 3x + 2} <= 2x + 3`
`-> 2x^2 - 3x + 2 <= 4x^2 + 12x + 9`
`-> 2x^2 + 15x + 7 >= 0`
`->` \(\left[ \begin{array}{l}x ≤ -7\\x ≥ -\dfrac{1}{2}\end{array} \right.\)
`-> x in (-infty; -7] cup [-1/2; +infty)`
`text{Bài 4}`
`(2x + 5)(2x^2 - 1) <= 0`
`->` \(\left\{ \begin{array}{l}\left[ \begin{array}{l}2x + 5 ≥ 0\\2x^2 - 1 ≤ 0\end{array} \right.\\\left[ \begin{array}{l}2x + 5 ≤ 0\\2x^2 - 1 ≥ 0\end{array} \right.\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x ≤ -\dfrac{5}{2}\\-\dfrac{\sqrt{2}}{2} ≤ x ≤ \dfrac{\sqrt{2}}{2}\end{array} \right.\)
