Posted by **sabrina** on Monday, July 11, 2011 at 5:04pm.

The height of a projectile fired upward is given by the formula

s = v0t − 16t2,

where s is the height in feet,

v0

is the initial velocity, and t is the time in seconds. Find the time for a projectile to reach a height of 96 ft if it has an initial velocity of 128 ft/s. Round to the nearest hundredth of a second.

- math -
**Reiny**, Monday, July 11, 2011 at 5:59pm
so you are solving

96 = 128 - 16t^2

16t^2 = 32

t = √2

I will leave the rounding to you.

- ignore last reply - math -
**Reiny**, Monday, July 11, 2011 at 6:04pm
should have been

96 = 128t - 16t^2

16t^2 - 128t + 96 = 0

t^2 - 8t + 6 = 0

t = 4 + √10 or 4 - √10

There are two possible answers, since the height of 96 feet is reached on its upwards flight, and then again when it comes back down.

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