Posted by **jennifer** on Tuesday, September 30, 2008 at 10:02am.

A toy rocket is launched vertically upward from ground level. This is represented as f(t) = -16t^2 + 128t where t is the time in second and f(t) is the height of the rocket in feet. When will the rocket hit the ground?

divide both sides by -16

0 = -16t^2 + 128t

0 = t^2 - 8t

0 = t(t-8t)

0 = t

0 = t-8

add 8 to both sides

8 = t

the rocket will hit the ground in 8 seconds.

can you tell me if I'm correct?

- MATH -
**Qun**, Tuesday, September 30, 2008 at 10:44am
Yes, it is right.

- MATH -
**tony**, Tuesday, September 30, 2008 at 11:09am
no

- MATH -
**jennifer**, Tuesday, September 30, 2008 at 12:24pm
what's wrong with it?

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