Respuesta :

(81^-0.25)^3 = ( 1 / (81^0.25) )^3 

81^.025 is the 4th root of 81 which is 3 
Therefor 
( 1 / (81^0.25) )^3 = (1/3)^3 

(1/3)^3 = 1/27 <-----

Hope I Helped You!!! :-)

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