To solve the equation \( x^2 - 64 = 0 \), we can start by isolating \( x^2 \):
\[ x^2 = 64 \]
Next, we take the square root of both sides:
\[ x = \pm \sqrt{64} \]
Since \( \sqrt{64} = 8 \), we have:
\[ x = 8 \quad \text{or} \quad x = -8 \]
Thus, the solutions are:
- \( x = 8 \)
- \( x = -8 \)
From the options provided:
- A. 8 (is a solution)
- B. 0 (is not a solution)
- C. 64 (is not a solution)
- D. -8 (is a solution)
Therefore, the correct answers are:
A. 8 and D. -8