I've tried this problem 4 times now and i keep getting the wrong answer. I thought it would be a simple quadratic equation problem but I'm just not getting it.

A baseball is “popped” straight up by a batter. The height of the ball above the ground is given by the function , wheretis time in seconds after the ball leaves the bat andyis the height of the ball in feet.

It wants me to find at what time the ball hits the ground.