\(a,\left|x-9\right|=-5\)
\(x-9=-5\)
Vậy \(x=4\)
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\(b,\left|6-2x\right|=\left|-1\right|\)
\(\left|6-2x\right|=1\)
\(\Rightarrow\left[{}\begin{matrix}6-2x=1\\6-2x=-1\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}2x=5\\2x=7\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=\dfrac{7}{2}\end{matrix}\right.\) Vậy \(x\in\left\{\dfrac{5}{2};\dfrac{7}{2}\right\}\)