Final answer:
The value of a is 8 if a² - 64 = 0 and a > 0.
Step-by-step explanation:
To find the value of a, given the equation a² - 64 = 0 and a > 0, we can solve the quadratic equation. First, we can rearrange the equation as a² = 64. Taking the square root of both sides, we have a = ±√(64) = ±8. Since a > 0, the value of a is 8.