Example 7: h = 16t^2 + 72t + 520

Suppose a particular “star” is projected from a firework at a starting height of 520 feet with an initial upward velocity of 72 ft/sec. 
 The equation: 
 h = 16t^2 + 72t + 520 
 gives the star’s height h in feet at time t in seconds. 
 a) How long will it take for the star to reach its maximum height? 
 
 b) What is the maximum height?