The height (in meters) of a shot cannonball follows a trajectory given by h(t) = -4.9t^2 + 14t - 0.4 at time t (in seconds). As an improper fraction, for how long is the cannonball above a height of 6 meters? Please show steps. Thank you!

Solve for 6 = -4.9t^2 + 14t - 0.4 and you will have 2 positive numbers. First one is when cannonball reach 6 meters and second is when after it starts to fall down to 6 meters. I estimate first number to be 0.5 and the second to be 2.5 so the duration is 2 seconds.