At what time will she touch the water in the pool?
(a) 30 seconds
(b) 2 seconds
(c) 1.5 seconds
(d) 0.5 seconds
(a) 30 seconds
(b) 2 seconds
(c) 1.5 seconds
(d) 0.5 seconds
(b) 2 seconds
Explanation:
at t=0, Annie’s height is 48ft
So, at t =0, h should be equal to 48
Putting h=0 in equation
= h (t) = `-16t^{2}` + 8t + 48
= h (0) = `-16t^{2}` + 8t + 48
= `-16t^{2}` + 8t + 48 = 0
= -4 (`4t^{2}` - 2t - 12) = 0
= `4t^{2}` - 2t - 12 = 0
Now, Solving by splitting the middle term
= `4t^{2}` - 8t + 6t - 12 = 0
= 4t (t - 2) + 6 (t - 2) = 0
= (4t + 6) (t - 2) = 0
t = `-6/4` = `-3/2` and t = 2
t = 2 (time can't be negative)
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