posted by Anonymous .
If a rocket is propelled upward from ground level, it's height in meters after t seconds is given by h=-9.8t^2+88.2t. During what interval of time will the rocket be higher than 137.2m?
I divided both sides by -9.8 which gave me
But I can't remember what step is next please help. Thanks in advance:-)
137.2 = -9.8t^2 + 88.2t
Divide both sides by -9.8 (whatever operation you do to one side of an equation you must do to the other side as well):
(137.2)/-9.8 = (-9.8t^2 + 88.2t)/-9.8
-14 = t^2 - 9
Set the equation equal to 0:
0 = t^2 - 9 + 14
Try to factor:
0 = (t - 7)(t - 2)
Set the factors equal to 0:
t - 7 = 0
t - 2 = 0
Therefore, the two solutions are t = 2 and t = 7.
Interval: 2 < t < 7