select all of the following expressions that are equivalent to 9^1/2

3^1/2 * 3^1/2

\root(6)(27)

27^1/3 * 3^1/2

81^1/2 * 81^1/2

729^1/6

81^1/3 * 81^1/3

81^1/4 * 81^1/4

- \root(6)(27)

- 27^1/3 * 3^1/2
- 729^1/6