Answer:
t = 1.5 seconds
Step-by-step explanation:
Given that d = −4t^2 + 2t + 6,
where d = distance above the water and
t = seconds.
Let assume that it's a perfect parabola
At the symmetry
t = -b/2a
Where a = -4, b = 2
t = -2/2(-4)
t = 1/4
To determine how long it will take a diver to reach the water’s surface
d = −4t^2 + 2t + 6
At water surface d =0
4t^2 - 2t - 6 = 0
Factorizing the above equation leads to
4t^2 + 4t - 6t - 6 = 0
4t(t + 1) -6(t + 1) = 0
4t - 6 =0
4t = 6
t = 6/4= 3/2 = 1.5 seconds
Since t can't be negative so we ignore the second factor.
