Đáp án: x=2
Giải thích: $(\frac{1}{3})^{2x-1}-(\frac{1}{3})^{2}=\frac{-2}{27}$
⇔$\frac{1}{3^{2x-1}}-\frac{1}{9}=\frac{-2}{27}$
⇔$\frac{9-3^{2x-1}}{9.3^{2x-1}}=\frac{-2}{27}$
⇔243-27.3$^{2x-1}$=-18.3$^{2x-1}$
⇔243=9.3$^{2x-1}$
⇔27=3$^{2x-1}$
⇔3$^{3}$=3$^{2x-1}$
⇔2x-1=3
⇔x=2