Question

A waterfall has a height of 900 feet. A pebble is thrown upward from the top of the falls with an initial velocity of 12 feet per second. The​ height, h, of the pebble after t seconds is given by the equation h equals negative 16 t squared plus 12 t plus 900. How long after the pebble is thrown will it hit the​ ground?

Answer 1

A graphing calculator shows the time to be 7.884 seconds.

_____
The quadratic formula tells you the time is
.. t = (-12 -√(12^2 +4*16*900))/(-32) = (3/8)*(1 +√401) . . . seconds