A model rocket fired from the ground at time t can be modeled by the equation h= -490t² + 1120t. When is the height of the model
rocket 640 centimeters?
1 answer:
9514 1404 393
Answer:
t = 1 1/7 ≈ 1.1429 seconds
Step-by-step explanation:
Filling in the given height, we can solve for t:
640 = -490t^2 +1120t
49t^2 -112t +64 = 0 . . . . . divide by 10, put in standard form
(7t -8)^2 = 0
t = 8/7 . . . . . . . the value of t that makes the factor(s) zero
The model rocket will reach its maximum height of 640 cm after 1 1/7 seconds.
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