Laurie throws a tennis ball toward her dog from a height of 4.5 ft. the initial vertical velocity of the ball is 18 ft/s. at the same time as laurie throws the ball, her dog jumps with an initial vertical velocity of 21 ft/s. when the dog jumps, its mouth is 1.5 ft above the ground. which system models the height of the tennis ball and the height of the dog's mouth over time?

what does the t-coordinate of the solution h = -16t2 + 18t + 4.5 and h = -16t2 + 21t + 1.5 to this system represent?

a) the time at which the ball and the dog hit the ground
b)the time at which the ball and the dog begin moving
c)the time at which the ball and the dog's mouth are at the same height