SOLUTION: The height of ball that is launched from an initial of 84 feet with an initial upward velocity of 20 feet per second is given by the function: h(t)= -16t^2+20t+84 where h rep

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: The height of ball that is launched from an initial of 84 feet with an initial upward velocity of 20 feet per second is given by the function: h(t)= -16t^2+20t+84 where h rep      Log On


   



Question 1113207: The height of ball that is launched from an initial of 84 feet with an initial upward velocity of 20 feet per second is given by the function:
h(t)= -16t^2+20t+84
where h represents the height of the ball at t seconds. How long will it take for the ball to hit the ground?

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!

h(t)= -16t%5E2%2B20t%2B84
when it hits the ground h(t) =0
-16t%5E2%2B20t%2B84=0
solve the quadratic equation.
4t^2 -5t-21=0
4t^2 -12t+7t-21=0
4t(t-3) +7(t-3)=0
(t-3)(4t+7)=0
t= 3
after 3 seconds