Respuesta :

81^(-1/4) is the same as the fourth root of (1/81). Which can be written as 4th root of 1 divided by the 4th root of 81.
The 4th root of 1 is 1 (because 1x1x1x1x1=1).
The 4th root of 81 is 3 (because 3x3x3x3=81).
So 81^(-1/4) = 1/3