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An arrow is fired into the air with an initial upward velocity of 64 feet per second from the top of a building 80 feet high.
The equation that gives the hight of the arrow at any time t is h = 80 +64t-16t^2 Find the times at which the arrow
will be 128 feet in the air?

Respuesta :

Answer:

128 = 80 + 64 t - 16 t^2

8 = 5 + 4 t - t^2

3 = t (4 - t)

Inspection shows the equation is solved if

t = 1   and t = 3

Plug into original equation to check

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