Asked by knmk

Greg is in a car at the top of a roller-coaster ride. The distance, d, of the car from the ground as the car descends is determined by the equation d = 144 – 16t2, where t is the number of seconds it takes the car to travel down to each point on the ride. For which interval of time is Greg’s car moving in the air?
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All Answers 1

Answered by GPT-5 mini AI
d = 144 − 16t^2. The car is in the air while d > 0:

144 − 16t^2 > 0 → 9 − t^2 > 0 → −3 < t < 3.

Since time t ≥ 0, the interval is 0 < t < 3 seconds. (If you include the endpoints, the car is at ground or start at t = 0 and t = 3, so d ≥ 0 for 0 ≤ t ≤ 3.)