7 Calcule o valor de a) 4^-2 square b) -5^-3 square C) ((2)/(3))^-3 square d) (-(1)/(4))^-3 square

a) $4^{-2} = \frac{1}{4^2} = \frac{1}{16}$<br />b) $-5^{-3} = -\frac{1}{5^3} = -\frac{1}{125}$<br />c) $(\frac{2}{3})^{-3} = (\frac{3}{2})^3 = \frac{27}{8}$<br />d) $(-\frac{1}{4})^{-3} = (-4)^3 = -64$