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.
h = -16t2 + 18t + 4.5 and h = -16t2 + 21t + 1.5

What does the t-coordinate of the solution to this system represent?

the time at which the ball and the dog hit the ground

the time at which the ball and the dog begin moving

the time at which the ball and the dog's mouth are at the same height

Question

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.
h = -16t2 + 18t + 4.5 and h = -16t2 + 21t + 1.5

What does the t-coordinate of the solution to this system represent?

the time at which the ball and the dog hit the ground

the time at which the ball and the dog begin moving

the time at which the ball and the dog's mouth are at the same height