Homework Help: MATH

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?
    - MATH - David Q, Tuesday, September 30, 2008 at 1:16pm
      There's nothing wrong with it: it's correct.
      - MATH - jennifer, Tuesday, September 30, 2008 at 3:04pm
        Thanks!

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