The function f(x) = −x2 − 9x + 36 shows the relationship between the vertical distance of a diver from a pool's surface f(x), in feet, and the horizontal distance x, in feet, of a diver from the diving board. What is a zero of f(x), and what does it represent?
x = 3; the diver jumps in the pool at 3 feet per second
x = 3; the diver hits the water 3 feet away horizontally from the board
x = 12; the diver hits the water 12 feet horizontally from the board
x = 12; the diver jumps in the pool at 12 feet per second