Answer:
5 seccs
Step-by-step explanation:
Given the modeled function of the height expressed as;
h(t)=-16t^2+64t+80
The ball hits the ground when h(t) = 0 (when the height is zero)
Substitute into the function and find t;
0 =-16t^2+64t+80
divide through by -16
0 = t²-4t-5
Factorize;
t²-4t-5 = 0
t²-5t+t-5 = 0
t(t-5)+1(t-5) = 0
(t+1)(t-5) = 0
t + 1 = 0 and t-5 = 0
t = -1 and t = 5
Time can't be negative
Hence it will take the ball 5secs before it hits the ground
