Bjr,
a) [tex]2^{-3} = \dfrac{1}{2^3}= \dfrac{1}{8}=0,125 [/tex]
b) [tex]5^{-2}= \dfrac{1}{5^2}= \dfrac{1}{25}=0,04[/tex]
c) [tex]3^{-4}= \dfrac{1}{3^4}= \dfrac{1}{81}[/tex]
d) [tex]-3^{-3}= \dfrac{1}{-3^3}= - \dfrac{1}{27}[/tex]
e) [tex]-3^4=[(-3)^2]^2=(-3)^2*(-3)^2=9*9=81[/tex]