Quick suppose a particle is moving along the x-axis. the position, measured in feet, of the particle can be modeled by the quadratic equation y = 3x2 − 12x − 9, where x is time, in seconds. what does the number −9 represent for the quadratic function? the particle is 9 feet to the left of the origin. the particle is moving left 9 feet per second. the particle is accelerating at −9 feet per second squared. the particle has stopped at 9 seconds.