Here the link of my question on wolframalpha.com
http://www.wolframalpha.com/input/?i=is+%28%28x%29^%282%2F3%29%29+equals+to+%28%28%28x%29^2%29^%281%2F3%29%29&a=^_Real
I guess based on definitions and propertied of square root, exponentials and logarithms
((x)^(2/3)) == ((x^2)^(1/3))
True for x>=0.
((Log[x])^2)^(1/3) == ((Log[x])^(1/3))^2
true for x>=1 & x<=-1
