To determine how far the firework will travel before it reaches the ground, we need to solve the quadratic equation given by:
\[ 0 = -x^2 + 15x \]
We can rearrange this equation to:
\[ -x^2 + 15x = 0 \]
Factoring out \( x \):
\[ x(-x + 15) = 0 \]
Setting each factor equal to zero gives us the potential solutions:
- \( x = 0 \)
- \( -x + 15 = 0 \) → \( x = 15 \)
The two solutions are \( x = 0 \) and \( x = 15 \).
The solution \( x = 0 \) represents the starting point when the firework is launched, and \( x = 15 \) is the distance it travels horizontally before it hits the ground.
Thus, the firework will travel 15 feet before it reaches the ground.
The correct response is: 15 feet.