+0  
 
0
53
1
avatar

The equation y = -16t^2 - 80t + 54 describes the height (in feet) of a ball thrown downward at 80 feet per second from a height of 54 feet from the ground, where t represents time, measured in seconds. In how many seconds will the ball hit the ground? Express your answer as a decimal rounded to the nearest hundredth.

 May 8, 2021
 #1
avatar+120287 
+1

When it  hits  the  ground, y   =   0

 

So we need to solve  this  :

 

-16t^2  - 80t  +  54  =   0               divide  through  by  - 2

 

8t^2 + 40t  -  27   =  0

 

Using  the   Quad  Formula, we have

 

 

t  = [ -40 +  sqrt (40^2  - 4*8*-27)]/ (2*8)    ≈   .60       sec

 

 

cool cool cool

 May 8, 2021

28 Online Users

avatar
avatar