Tính a) (-4/5)^4

a) ${\left(-\frac{4}{5}\right)}^4=\left(-\frac{4}{5}\right).\left(-\frac{4}{5}\right).\left(-\frac{4}{5}\right).\left(-\frac{4}{5}\right)=\frac{\left(-4\right).\left(-4\right).\left(-4\right).\left(-4\right)}{\mathrm{5.5.5.5}}=\frac{{\left(-4\right)}^4}{5^4}=\frac{256}{625}.$

b) (0,7)³ = (0,7).(0,7).(0,7)$=\frac{7}{10}.\frac{7}{10}.\frac{7}{10}=\frac{7^3}{{10}^3}=\frac{343}{1000}=\mathrm{0,343.}$