a.
[tex] \frac{1}{81} = \frac{1}{ {3}^{4} } = {3}^{ - 4} [/tex]
b.
[tex]0.001 = {10}^{ - 3} [/tex]
c.
[tex]0.25 = \frac{1}{4} = \frac{1}{ {2}^{2} } = {2}^{ - 2} [/tex]
d.
[tex] \frac{1}{16} = \frac{1}{ {2}^{4} } = {2}^{ - 4} [/tex]
e.
[tex] \frac{1}{10} = {10}^{ - 1} [/tex]
