Question

Jerald jumped from a bungee tower. If the equation that models his height, in feet, is h = –16t2 + 729, where t is the time in seconds, for which interval of time is he less than 104 feet above the ground?
t > 6.25
–6.25 < t < 6.25
t < 6.25
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Answer 1

Solve -16t^2 + 729 < 104:
-16t^2 < -625 ⇒ t^2 > 625/16 ⇒ |t| > 25/4 = 6.25.
Since time t ≥ 0, the physical solution is t > 6.25 (i.e., (6.25, ∞)).