Math help needed!

Question

A ball is thrown from a height of 157

 feet with an initial downward velocity of 9/fts

. The ball's height h

 (in feet) after t

 seconds is given by the following.

=h−157−9t16t2

How long after the ball is thrown does it hit the ground?

Answer 1

h=-16t^2 -9t+ 157=0

t= -9/32 +(1/32)sqr(81+64(157)

= (-9+sqr(10129)

=91.64/32

= about 2.86 seconds to hit the ground