Holly plays tennis on the school tennis team. She can hit a tennis ball really high in the air. She learned that the quadratic equation y = -6x2 + 36x could be used to determine the
height of a tennis ball after it was hit with a tennis racket (y = the height of the tennis
ball in feet, x = seconds after the ball is hit with the racket).
a.
How long does it take for the ball to hit the ground? How can you tell?
b.
What is the highest point reached during the flight of the ball? How do you know?
C.
When was the ball exactly 48 feet off the ground? Explain your reasoning.