Posted by Anonymous on .
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?
h=9.8t^2+ 88.2t
I divided both sides by 9.8 which gave me
t^2=9
But I can't remember what step is next please help. Thanks in advance:)

algebra 
MathGuru,
The equation:
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