what is the simplest form of the radical expression 4^4 sqrt 2x+6^4 sqrt 2x

The first thing you can do in this case is to add both roots, since both have the same base.
 4 ^ 4 sqrt 2x + 6 ^ 4 sqrt 2x =
 10 ^ 4 sqrt 2x
 Then, the next thing you can do is rewrite the function as
 10 ^ 4 sqrt 2x = 10 * (2x) ^ (1/4)
 answer
 The simple form of the radical expression is
 10 * (2x) ^ (1/4)