The height of a golf ball in the air can be modeled by the equation , where h is the height in the feet of the ball after t seconds. a. how long is the ball in the air?

For this case we have the following equation:
 h (t) = - 16t ^ 2 + 76t
 We must find the time that was in the air.
 For this we equate the equation to zero.
 -16t ^ 2 + 76t = 0
 We look for the roots of the polynomial.
 For this, we rewrite:
 -4t * (4t-19) = 0
 Which roots are:
 t = 0
 t = 19/4
 Therefore, the time it was in the air was:
 t = 19/4
 
 t = 19/4 seconds