The expression 81x8y4z16 is given. We need to find the fourth root of this expression.
We can break this in two parts. First find the square root. Then take the square root of the product we get is the last step.
So, 2√81x8y4z16=9x4y2z8
⇒2√9x4y2z8=3x2yz4.
Hence, the answer is 3x2yz4.