Hi - i am not sure how to solve this - A waterfall has a height of 1200 feet. A pebble is thrown upward from the top of the falls with an initial velocity of 20 feet per second. Theheight, h, of the pebble after t seconds is given by the equation h equals negative 16 t squared plus 20 t plus 1200

h=16t2+20t+1200. How long after the pebble is thrown will it hit theground?

The pebble will hit the ground about

nothing seconds after it is thrown.