The height (in meters) of a shot cannonball follows a trajectory given by h(t) = -4.9t^2 + 18t - 0.4 at time t (in seconds). As an improper fraction, for how long is the cannonball above a height of 6 meters?
Set h(t) = 6
6 = -4.9t^2 + 18t- .4
0 = -4.9t^2 + 18t - 6.4 now use quadratic formula to solve for t.....
you will get two 't' values ...the time above 6 m will be the time between the two values