Question

A hovercraft takes off from a platform. Its height (in meters), xxx seconds after takeoff, is modeled by: h(x)=-3(x-3)^2+108

How many seconds after takeoff will the hovercraft land on the ground?

Answer 1

9 Seconds

Explanation:

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Answer 2

For this case we have the following function:

`h (x) = - 3 (x-3) ^ 2 + 108`

By the time of the landing we have:

`-3 (x-3) ^ 2 + 108 = 0`

From here, we clear the value of x.

We have then:

`-3 (x-3) ^ 2 = -108`

`(x-3) ^ 2 = (-108)/(- 3)`

`(x-3) ^ 2 = 36`

Discarding the negative root we have:

`(x-3) = √(36)`

`x = 6 + 3`

`x = 9`

Answer:

9 seconds after takeoff the hovercraft will land on the ground