Final answer:
The ball described by the parabola y = -x^2 + 4 will hit the ground 2 units away from the building. To find this distance, we set y to 0 and solve for x, which gives us ±2; we use the positive value since we are measuring distance from the building.
Step-by-step explanation:
The question asks us to find out at how many feet from the building the ball hit the ground, given the position of the ball is determined by the parabola y = -x^2 + 4. To find when the ball hits the ground, we need to solve for x when y is 0, which represents the ground level.
Setting the equation to 0, we get 0 = -x^2 + 4. Solving for x, we would have x^2 = 4, so x equals ±2. Since we're dealing with distance from the building where the ball is thrown horizontally, we'll take the positive value of x.
Therefore, the ball will hit the ground 2 units (we are using units instead of feet as the question doesn't specify the units) away from the building. If we need to convert this to feet, assuming each unit is one foot, the ball will hit the ground 2 feet from the building.