Tìm x biết: ${\left( {\frac{3}{4}} \right)^{3x - 1}} = \frac{{27}}{{64}}$.

${\left( {\frac{3}{4}} \right)^{3x - 1}} = \frac{{27}}{{64}}$

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

⇔ 3x – 1 = 3

⇔ 3x = 4

⇔ x = $\frac{4}{3}$

Vậy x = $\frac{4}{3}$.