a)
3^{-4}=(\frac{1}{3})^4=\frac{1}{81}
(-4)^{-3}=(-\frac{1}{4})^3=-\frac{1}{64}
-4^{-2}=-(\frac{1}{4})^2=-\frac{1}{16}
b)
(\frac{1}{3})^{-2}=3^2=9
(-\frac{2}{3})^{-3}=(-\frac{3}{2})^3=-\frac{27}{8}=-3\frac{3}{8}
(-\frac{3}{2})^{-2}=(-\frac{2}{3})^2=\frac{4}{9}
c)
(2\frac{1}{3})^{-2}=(\frac{7}{3})^{-2}=(\frac{3}{7})^2=\frac{9}{49}
(-1\frac{1}{4})^{-2}=(-\frac{5}{4})^{-2}=(-\frac{4}{5})^2=\frac{16}{25}
0,25^{-3}=(\frac{1}{4})^{-3}=4^3=64
d) (\sqrt7)^{-4}=[(\sqrt7)^2]^{-2}=7^{-2}=(\frac{1}{7})^2=\frac{1}{49}
(\frac{\sqrt5}{5})^{-2}=(\frac{5}{\sqrt5})^2=\frac{25}{5}=5
(-\frac{\sqrt3}{2})^{-6}=(-\frac{2}{\sqrt3})^6=(\frac{2}{\sqrt3})^6=\frac{2^6}{\sqrt{(3^3)^2}}=\frac{64}{3^3}=\frac{64}{27}=2\frac{10}{27}