Câu 1.21 :
a. $(-3)^{7}$= - 2187 = > $(-3)^{8}$=$(-3)^{7}$.(-3)=(- 2187).(-3) = 6561
b. $\left ( -\frac{2}{3} \right )^{11}$= $\frac{-2 048}{177 147}$ => $\left ( -\frac{2}{3} \right )^{12}$ = $\left ( -\frac{2}{3} \right )^{11}$. ($-\frac{2}{3}$)= ($\frac{-2 048}{177 147}$). ($-\frac{2}{3}$)= $\frac{4 096}{531 441}$