For this case we have the following expression:
 ((6x ^ 3) / (3x ^ 4)) ^ 2
 By power properties we can rewrite the function as:
 (6x ^ (3 * 2)) / (3x ^ (4 * 2))
 (6x ^ 6) / (3x ^ 8)
 Then, simplifying we have:
 2x ^ (6-8)
 2x ^ -2
 2 / x ^ 2
 Answer:
 The simplified expression is:
 2 / x ^ 2