\(\left(\dfrac{1}{2}x-\dfrac{2}{3}\right)^2=\dfrac{1}{4}\)\(=\left(\dfrac{1}{2}\right)^2\)\(=\left(\dfrac{-1}{2}\right)^2\)
\(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{2}x-\dfrac{2}{3}=\dfrac{1}{2}\\\dfrac{1}{2}x-\dfrac{2}{3}=\dfrac{-1}{2}\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\dfrac{7}{3}\\x=\dfrac{1}{3}\end{matrix}\right.\)
\(\Rightarrow N^o\)\(phương\) \(trinh\) \(la\)\(S=\left\{\dfrac{1}{3};\dfrac{7}{3}\right\}\)
T.I.C.K mình nhé!! ^_^