exponents

(16a^-2)^-1/2     ....applying the rule (a^m)ⁿ = a ^m*n  ....we have

(16)^-1/2   * (a^-2) ^-1/2   =

(4²) ^-1/2  * (a ^-2) ^-1/2  =

4^-1  * a  =

(1 / 4) * a  =

a / 4