应用题When a toy rocket is shot into the air,the height is h=-0

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应用题
When a toy rocket is shot into the air,the height is h=-0.332t^2 + 3.32t where h is the height in metres and t is the time in seconds.
a)At what time(s) is the rocket at a height of 3 metres?(Answer correct to the nearest tenth)
b) For how long is the rocket at a hegiht of 3 metres or higher?
请演算这道题,请写出过程,
oh forgot to mention to please use the quadratic formula to solve.
Quadratic Formula:x=-(b)+/- square root of b^2-4(a)(c)
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2(a)

from the questions know when h=3m
then -0.332t^2 + 3.32t =3(up)or h(max)-gt^2/2=3(down) g=9.8m/s^2
h(max)=8.3m（when t=5s)
so t=1.0045s or t=5+1.0252=6.0252s
At this time(s) the rocket at a height of 3 metres.
b)from a) know the answer
For 1.0045s or 6.0252s the rocket at a hegiht of 3 metres or higher.
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