Cách làm cho bạn:
a) x : $(\frac{3}{4})^{3}$ = $(\frac{3}{4})^{2}$ $\Rightarrow$ x = $(\frac{3}{4})^{2}$ . $(\frac{3}{4})^{3}$ $\Rightarrow$ x = $(\frac{3}{4})^{5}$ $\Rightarrow$ x = $\frac{243}{1024}$;
b) $(\frac{2}{5})^{5}$ . x = $(\frac{2}{5})^{8}$ $\Rightarrow$ x = $(\frac{2}{5})^{8}$ : $(\frac{2}{5})^{5}$ $\Rightarrow$ x = $(\frac{2}{5})^{3}$ $\Rightarrow$ x = $\frac{8}{125}$.
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