Đáp án:
$\left[\begin{array}{l}x = \dfrac53\\x = -\dfrac13\end{array}\right.$
Giải thích các bước giải:
$\begin{array}{l}\quad (3x-2)^4 = 81\\ \Leftrightarrow (3x-2)^4 = 3^4\\ \Leftrightarrow |3x - 2| = 3\\ \Leftrightarrow \left[\begin{array}{l}3x - 2 = 3\\3x - 2 = -3\end{array}\right.\\ \Leftrightarrow \left[\begin{array}{l}3x =5\\3x =-1\end{array}\right.\\\Leftrightarrow \left[\begin{array}{l}x = \dfrac53\\x = -\dfrac13\end{array}\right.\\ Vậy\,\,x = \dfrac53 \,\,hoặc\,\,x = -\dfrac13\end{array}$
