divide and simplify if possible

Sqrt 81x^8 / sqrt 3x = 9x^4 / sqrt 3x is correct but now you need to rationalize the denominator to finish simplifying

To rationalize the denominator, we need to multiply the numerator and denominator by the square root of 3x:

(9x^4 / sqrt 3x) * (sqrt 3x / sqrt 3x) = 9x^4 * sqrt 3x / 3x
= 9x^4 * sqrt 3 / 3
= 3x^4 * sqrt 3

Therefore, the simplified and rationalized form of the expression is 3x^4 * sqrt 3.