Answer :
With fraction exponents, you first raise the base (in this case -216) to the numerator, and then take the root (in this case cube root) of that number.
The y simplified answer would be 1/cuberoot(-216^4)
-216^-4 = 1/2,176,782,336
The cuberoot of that number is 0.000772
The y simplified answer would be 1/cuberoot(-216^4)
-216^-4 = 1/2,176,782,336
The cuberoot of that number is 0.000772