What would the numerator and denominator be? (picture included)

Simply take the power within the root (I.e. 4) as the numerator of the fraction, and the number of the root (I.e. 7) as the denominator of the fraction.

A way of understand would be using the expression (square root)4. 4 can be changed to 2^2. The power WITHIN the root will then be 2, which will be the numerator of the fraction. The power OF the root itself is 2 as well, which is the denominator of the fraction. This will leave us with 2^(2/2) = 2^1 = 2, which is correct; square root of 4 is 2 indeed.

Hope this helps! :)