First, we can use this rule for exponents to eliminate the negative exponent:
x^color(red)(a) = 1/x^color(red)(-a)
1000^color(red)(-2/3) = 1/1000^color(red)(- -2/3) = 1/1000^color(red)(2/3)
We can next rewrite the exponent as:
1/1000^color(red)(2/3) = 1/1000^(1/3 xx 2)
And then use this rule to rewrite the expression again:
x^(color(red)(a) xx color(blue)(b)) = (x^color(red)(a))^color(blue)(b)
1/1000^(color(red)(1/3) xx color(blue)(2)) = 1/(1000^(color(red)(1/3)))^color(blue)(2)
We can convert the term within the parenthesis to radical form using this rule:
x^(1/color(red)(n)) = root(color(red)(n))(x)
1/(1000^(color(red)(1/3)))^color(blue)(2) = 1/(root(color(red)(3))(1000))^color(blue)(2) = 1/10^color(blue)(2) = 1/100