If an object is dropped from a height of 126 feet, the function h(t)=-16t^2+126 gives the height of the object after t seconds. Approximately when will the object hit the ground?

Answer 1

solve for t when h=0.
16t^2 = 126
...

Answer 2

set the function to 0 and solve. so it would be 0 = -16t^2+126 and solve for t.