Bạn ơi , 3x - 1 là số mũ phải không . Gỉa sử vậy , ta có :

\(\frac{256}{81}=\frac{4^4}{\left(-3\right)^4}=\frac{1}{\frac{\left(-3\right)^4}{4^4}}=\frac{1}{\left(\frac{-3}{4}\right)^4}=\left(\frac{-3}{4}\right)^{-4}=\left(\frac{-3}{4}\right)^{3x-1}\)=> 3x - 1 = -4 => 3x = -4 + 1 = -3  

=> x = -3 : 3 = -1 

\(\left(\frac{-3}{4}\right)^{3x-1}=\left(\frac{4}{3}\right)^4=\left(\frac{1}{\frac{3}{4}}\right)^4\left[\left(\frac{3}{4}\right)^{-1}\right]^4=\left(\frac{3}{4}\right)^{-4}=\left(-\frac{3}{4}\right)^{-4}\) 

(Lũy thừa số mũ chẵn thì \(a^x\)= \(\left(-a\right)^x\))

\(\Rightarrow\)3m - 1 = -4 \(\Rightarrow\)3m = -3 \(\Rightarrow\)m = -1

😅😅😅

\(\left(\frac{-3}{4}\right)^{3x-1}=\frac{81}{256}\)

\(\Rightarrow\left(\frac{-3}{4}\right)^{3x-1}=\left(\frac{-3}{4}\right)^4\)

\(\Rightarrow3x-1=4\)

\(\Rightarrow3x=4+1\)

\(\Rightarrow3x=5\)

\(\Rightarrow x=5:3\)

\(\Rightarrow x=\frac{5}{3}\)

Vậy  \(x=\frac{5}{3}\)

_Chúc bạn học tốt_

\(\left(\frac{3}{4}\right)^{3x}=\frac{81}{256}\)

\(\left(\frac{3}{4}\right)^{3x}=\left(\frac{3}{4}\right)^4\)

\(3x=4\)

\(x=\frac{4}{3}\)

Chúc bạn học tốt ^^

\(\left(\frac{3}{4}\right)^{3x-1}=\frac{81}{256}\)

\(\left(\frac{3}{4}\right)^{3x-1}=\left(\frac{3^4}{4^4}\right)\)

\(\left(\frac{3}{4}\right)^{3x-1}=\left(\frac{3}{4}\right)^4\)

\(\Rightarrow3x-1=4\)

\(\Rightarrow3x=5\)

\(\Rightarrow x=\frac{5}{3}\)

phương an đề là :

\(\left(\frac{3}{4}\right)^{3x-1}=\frac{81}{256}\) mà 

\(\left(\frac{-3}{4}\right)^{3x-1}=\frac{256}{81}\)

\(\Rightarrow\left(\frac{-3}{4}\right)^{3x}:\left(\frac{-3}{4}\right)=\frac{256}{81}\)

\(\Rightarrow\left(\frac{-3}{4}\right)^{3x}=\frac{256}{81}.\left(\frac{-3}{4}\right)\)

\(\Rightarrow\left(\frac{-3}{4}\right)^{3x}=\frac{64}{27}\)

\(\Rightarrow\left(-\frac{3}{4}\right)^{3x}=\left(-\frac{4}{3}\right)^3\)

\(\Rightarrow1=\left(-\frac{4}{3}\right)^3.\left(-\frac{4}{3}\right)^{3x}\)

\(\Rightarrow1=\left(-\frac{4}{3}\right)^{-x}\)

\(\Rightarrow1=\left(-\frac{3x}{4}\right)\)

\(\Rightarrow1=-3x:4\)

\(\Rightarrow-3x=4\)

\(\Rightarrow x=-\frac{4}{3}\)

Ta có:

\(\frac{256}{81}=\frac{4^4}{"-3"^4}=\frac{1}{\frac{"-3"^4}{4}}=\frac{1}{"\frac{-3}{4}"^4}="\frac{-3}{4}"^4="\frac{-3}{4}"^{3x-1}\Rightarrow3x-1=-4\Rightarrow3x=-4+1\)

\(=-3\)

\(\Rightarrow x=-3:1=-1\)

tớ làm bừa đấy sai thì thôi nha