A golf ball is hit and the motion of the ball is described by h = -3t2+15t where
h is the ball's height above the ground (in metres) and t is the time (in seconds).
Determine how long the ball is in the air.
well, h(t) = -3t(t-5)
so h=0 when t=0,5
so, whaddaya think?
and that -3t^2 tells me you're golfing on some exoplanet, since on earth h(t) would be -4.9t^2 + 15t