A rock is thrown down from a cliff that is 180 m high. The function h(t) = -5t^2 – 10t + 180 gives the approximate height of the rock<

Question

A rock is thrown down from a cliff that is 180 m high. The function
h(t) = -5t^2 – 10t + 180 gives the approximate height of the rock
above the water, where h(t) is the height in metres and t is the time
in seconds. When will the rock reach a ledge that is 105 m above
the water?

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Thu Cúc 4 years 2021-07-18T03:39:28+00:00 2 Answers 101 views 0

Answers ( )

  1. Nick
    0
    2021-07-18T03:40:38+00:00
    Reply

    &2&2..&&.!:&/33;73jdjduejsjxoeeudxhwkeod

  2. mit
    0
    2021-07-18T03:40:48+00:00
    Reply

    Answer:

    t = 3

    Step-by-step explanation:

    105 = -5t^2 -10t + 180

    -75 = -5t^2 -10t

    15 = t^2 +2t

    t^2 +2t -15 = 0

    (t+5)(t-3)

    t = -5, 3

    There’s no such thing as negative time so you use the positive answer

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