Explicación paso a paso:
[tex]a. \: \: \: \: \: {a}^{ - 4} = \frac{1}{ {a}^{4} } [/tex]
[tex]b. \: \: \: \: \: {3}^{ - 3} = \frac{1}{ {3}^{3} } [/tex]
[tex]c. \: \: \: \: {6}^{ - x} = \frac{1}{ {6}^{x} } [/tex]
[tex]d. \: \: \: {x}^{ - y} = \frac{1}{ {x}^{y} } [/tex]
