\(\left(x-\dfrac{2}{3}\right)^2-1=8\)
\(\Rightarrow\left(x-\dfrac{2}{3}\right)^2=9\)
\(\Rightarrow x-\dfrac{2}{3}=3\)
\(\Rightarrow x=\dfrac{11}{3}\)
\(\left(x-\dfrac{2}{3}\right)^2-1=8\)
<=> \(\left(x-\dfrac{2}{3}\right)^2=3^2\)
<=> \(\left|x-\dfrac{2}{3}\right|=3\)
<=> \(\left[{}\begin{matrix}x-\dfrac{2}{3}=3\left(ĐK:x\ge\dfrac{2}{3}\right)\\-x+\dfrac{2}{3}=3\left(x< \dfrac{2}{3}\right)\end{matrix}\right.\)
<=> \(\left[{}\begin{matrix}x=\dfrac{11}{3}\left(TM\right)\\x=-\dfrac{7}{3}\left(TM\right)\end{matrix}\right.\)
\(\left(x-\dfrac{2}{3}\right)^2-1=8\)
\(\Leftrightarrow\left(x-\dfrac{2}{3}\right)^2=9\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{2}{3}=3\\x-\dfrac{2}{3}=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{11}{3}\\x=-\dfrac{7}{3}\end{matrix}\right.\)