Natalie found a tennis ball outside a tennis court. she picked up the ball and threw it over the fence into the court. the path of the ball can be represents by h=-16t^2+18t+5.

To solve this exercise you must follow the proccedure below:

 a) Find the maximum height of the tennis ball:

  You have that the path of the ball can be represented by h=-16t²+18t+5. Then:

 t=-b/2a
 t=-18/2(-16)
 t=0.562

 h=-16t²+18t+5
 h=-16(0.562)²+18(0.562)+5
 h=10.06

 b) How long will it take to reach the ground?

 h=-16t²+18t+5

 h=0

 -16t²+18t+5=0

 You must apply the quadratic equation: 

 t=(-b±√(b^2-4ac))/2a

 a=-16
 b=18
 c=5

 When you substitute the values, you obtain:

 t=1.35