The equation \(y=-16t^2+28t+144\) describes the height y (in feet) at time t (in seconds) 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?
Plugging in different values of t, you can find that t = 5.5 works.
Sorry; I just tried that and its incorrect!
\(0=-15t^2+28t+144\\ t=\frac{-28\pm\sqrt{784+8640}}{-30}\\ t=\frac{-28\pm\sqrt{9424}}{-30}\\ t=\frac{+28+4\sqrt{589}}{30}\\ t\approx 4.17 sec\)
+660 
