\(\left(\frac{-3}{4}\right)^{3x-1}=\frac{81}{256}\)
\(\Rightarrow\left(\frac{-3}{4}\right)^{3x-1}=\left(\frac{-3}{4}\right)^4\)
\(\Rightarrow3x-1=4\)
\(\Rightarrow3x=4+1\)
\(\Rightarrow3x=5\)
\(\Rightarrow x=5:3\)
\(\Rightarrow x=\frac{5}{3}\)
Vậy \(x=\frac{5}{3}\)
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