The equation y = -16t^2 + 28t + 144 describes the height (in feet) of a ball tossed up in the air at 28 feet per second from a height of 144 feet from the ground. In how many seconds will the ball hit the ground?
+36916 When the ball hits the ground, h will = 0
0 = -16t^2 + 28t + 144 Use quadratic formula to find t .... throw out negative t values
a = -16 b = 28 c = 144
\(t = {-28 \pm \sqrt{28^2-4(-16)(144)} \over 2(-16)}\)
