Ta có: \(M=3-\left|\dfrac{1}{3}-2x\right|\\ =-\left|\dfrac{1}{3}-2x\right|+3\)
\(-\left|\dfrac{1}{3}-2x\right|\le0\forall x\\ \Rightarrow M\le3\\ \Leftrightarrow Max_M=3\Leftrightarrow\left|\dfrac{1}{3}-2x\right|=0\Leftrightarrow x=\dfrac{1}{6}\\ Vậy...\)