\(\left(4x-1\right)^3=-\dfrac{1}{27}\)
\(\Rightarrow4x-1=-\dfrac{1}{3}\)
\(\Rightarrow4x=\dfrac{2}{3}\Rightarrow x=\dfrac{1}{6}\)
\(\left(4x-1\right)^3=\left(-\dfrac{1}{27}\right)\Leftrightarrow4x-1=-\dfrac{1}{3}\Leftrightarrow4x=\dfrac{2}{3}\Leftrightarrow x=\dfrac{1}{6}\)