which of the following is equal to a^2/3, for all values of a?

Answer: 8

Given: 

Step 1: Simplify. 

Step 2: Use the exponent rule.

Step 3: Make the denominator common.

Step 4: Simplify the exponent into 1/2

Step 5: The square root of 64 is 8. 

(Explanation: 64^1/2 means the square root of 64, let's assume that some number is multiplied 2 times to get 64)