It helps if you know things like 4³=64 and ∛64 = 4 

Positive fractions can be written as radicals, but
negative exponents can't, so we have to put 1 over
them with a positive exponent.  Then we use the 
"fraction exponential to radical" rule, which is






Now we use the "fraction exponent to radical" rule



and since we know that ∛64 = 4

that becomes

 

and finally



Edwin