"Radicand" is the name for the expression inside a radical. Please put radicands in parentheses when posting questions!! From what you posted it is impossible to know how much of "3x^2y^8z^-1 divided by 625z" is inside the square root and how much of it is outside of the square root.
What is "5 square root"? Is it 5 times the square root? Or is it not really a square root but a "5th root". is called "the 5th root of 12" not "5 square root of 12". There are no square roots in !
Please re-post your problem using correct descriptions and parentheses to make the problem clear.