`a,|x - 9| ≥ 7`
`⇒` \(\left[ \begin{array}{l}x - 9 ≥ 7\\x - 9 ≥ -7\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x≥ 7 + 9\\x≥ -7 + 9 \end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x≥ 16\\x≥ 2\end{array} \right.\)
`b, |x - 5 | ≤ 19`
`⇒` \(\left[ \begin{array}{l}x-5≤19\\x-5≤-19\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x≤19+5\\x≤-19+5\end{array} \right.\)
`⇒` \(\left[ \begin{array}{l}x≤24\\x≤-14\end{array} \right.\)
`c,( x - 13 ) ² ≥ 9`
`⇒ ( x - 13 ) ² ≥ 3²`
`⇒ x - 13 ≥ 3`
`⇒ x ≥ 16`
`d, ( 3x + 5 )² ≤ 36`
`⇒ ( 3x + 5 )² ≤ 6²`
`⇒ 3x + 5 ≤ 6`
`⇒ 3x ≤ 1`
`⇒ x ≤ 1/3`
Xin hay nhất !
