Below you'll find the solution to this question:
A toy rocket is launched from the
rooftop of a building. The rocket's height, h(t), is modeled by the
equation h(t) = -16t² +80t + 96 after t seconds.
- How tall is the building?
- How long before the rocket hits
the ground at the base of the building?
- How high will the rocket be 5
seconds after take off?
- At
what time will the rocket be 160 feet above the ground?
Answers:
- The
building is 96 feet
tall.
- 0 = (t + 1)(t - 6) This gives us two possible answers: -1 and 6. However, -1 seconds doesn't make sense in the context of this word problem, so the only correct answer is 6
seconds.
- -400 + 400 + 96 = 96
feet
- 0 = (t - 1)(t - 4) This gives us two correct answers: 1
second and 4 seconds
after takeoff. If this doesn't make sense to you, draw a picture of the trajectory of the rocket.