Question

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02:50:34
The quadratic model f(x) = -5x2 + 200 represents the approximate height, in meters, of a ball x seconds after being
dropped. The ball is 50 meters from the ground after about how many seconds?
2.45
3.16
5.48
7.07
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Answer 1

≈ 5.48 sec

Explanation:

Equate the height f(x) to 50, that is

- 5x² + 200 = 50 ( subtract 200 from both sides )

- 5x² = - 150 ( divide both sides by - 5 )

x² = 30 ( take the square root of both sides )

x =
`√(30)` ≈ 5.48 ( to 2 dec. places )