\(\left(-\dfrac{3}{4}\right)^{3x-1}=\left(\dfrac{4}{3}\right)^4\)
\(\Leftrightarrow\left(-\dfrac{3}{4}\right)^{3x-1}=\dfrac{256}{81}=\dfrac{4^4}{\left(-3\right)^4}=\dfrac{1}{\left(-\dfrac{3}{4}\right)^4}=\left(-\dfrac{3}{4}\right)^{-4}=\left(-\dfrac{3}{4}\right)^{3x-1}\)\(\Leftrightarrow3x-1=-4\)
\(\Leftrightarrow3x=-3\)
\(\Leftrightarrow x=-1\)
Vậy x=-1