Question 118622
The Problem is: 81 with an exponent of -(3/4) 
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The negative sign means "invert".
The 3 means "cube"
The 4 in the denominator means "take the 4th root".
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You may do these in any order and still arrive at the right value.
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The best 1st step is to take the 4th root as that gives you a smaller
number to work with:
Taking the 4th rood you have 3^(-3)
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Now you can "invert" or "cube":
If you "invert" you get (1/3)^3
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If you now "cube" you get 1/27 as the final answer.
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Try the instruction in some other order and you will
get the same answer.
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Cheers,
Stan H.