To determine whether the equation \( y = 8 \times 0.84^x \) represents exponential growth, exponential decay, or neither, we look at the base of the exponential component, which is \( 0.84 \).
- If the base is greater than 1 (e.g., \( 2, 3, 10 \)), it represents exponential growth.
- If the base is between 0 and 1 (e.g., \( 0.5, 0.84 \)), it represents exponential decay.
Since \( 0.84 < 1 \), the equation represents exponential decay.
Thus, the correct answer is:
Exponential decay.