\(a)\left|x+\dfrac{1}{2}\right|=3\)
\(\Rightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=3\\x+\dfrac{1}{2}=-3\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=3-\dfrac{1}{2}\\x=-3-\dfrac{1}{2}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=\dfrac{-7}{2}\end{matrix}\right.\)
\(b)\left|2x-1\right|=-4\)
\(\Rightarrow\left|2x-1\right|=-4\)
\(\Rightarrow\left|x-1\right|=-4:2\)
\(\Rightarrow\left|x-1\right|=-2\)
Ta có: \(\left|x-1\right|\ge0\) mà \(-2< 0\)
Vậy ko có giá trị thỏa mãn đề bài.
