Cách làm cho bạn:
a. $x:(-\frac{1}{2})^{3}=-\frac{1}{2}$
<=> $x=-\frac{1}{2}.(-\frac{1}{2})^{3}$
<=> $x=(-\frac{1}{2})^{1+3}$
<=> $x=(-\frac{1}{2})^{4}$
<=> $x=\frac{1}{16}$
Vậy $x=\frac{1}{16}$.
b. $(\frac{3}{4})^{5}.x=(\frac{3}{4})^{7}$
<=> $x=(\frac{3}{4})^{7}:(\frac{3}{4})^{5}$
<=> $x=(\frac{3}{4})^{7-5}$
<=> $x=(\frac{3}{4})^{2}=\frac{9}{16}$
Vậy $x=\frac{9}{16}$.
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