Amir stands on a balcony and throws a ball to his dog, who is at ground level.
 The ball's height (in meters above the ground), xxx seconds after Amir threw it, is modeled by:
 h(x)=-(x-2)^2+16h(x)=−(x−2) 
 2
 +16h, left parenthesis, x, right parenthesis, equals, minus, left parenthesis, x, minus, 2, right parenthesis, squared, plus, 16
 How many seconds after being thrown will the ball hit the ground?