The function f (x) = - 10 (x) (x - 4) represents the approximate height of a projectile launched from the ground into the air with an initial velocity of 40 meters per second. How long, from launch to landing, does the projectile stay in the air? 0 seconds 1 second 2 seconds 4 seconds

The height of the project becomes zero when it hits the ground which is also the total time at which the projectile stays in the air. Equating the function to zero:

-10 (x) (x - 4) = 0

The roots of this quadratic equation are:

x = 0, and x=4

Therefore, the projectile stays in the air for

4 seconds