Verified answer

Resposta:

A)

[tex](1-\dfrac{2}{5})^{-2}=\\\\ \\ (\dfrac{5-2}{5})^{-2}=\\ \\ \\ (\dfrac{3}{5})^{-2}=(\dfrac{5}{3})^2=\dfrac{25}{9}[/tex]

B)

[tex](\dfrac{5}{4}-1)^{-3}=\\ \\ \\ (\dfrac{5-4}{4})^{-3}=\\ \\ \\ (\dfrac{1}{4})^{-3}=(\dfrac{4}{1})^3=\boxed{64}[/tex]