an arrow is shot into the air is 144t-4.9t^2 meters above the ground t seconds after it is released.During what period(s) of time is ht arrow above 68.6 meters?

Question

anonymous · Answer

a. 0.48 < t <28.90 seconds b. t <14 and t > 15.36 seconds c 14 < t < 15.39 seconds d. t < 0.48 and t > 28.90 seconds

cwrw238 · Answer

144 - 4.9t^2 = 68.6

solve this equation for t to give 2 instants in time when it was at this height

anonymous · Answer

I got -3.93 for t, is that right?

cwrw238 · Answer

I'm checking it out now 
I made a mistake first time

you have to solve 

-4.9t^2 + 144t -68.6 = 0

cwrw238 · Answer

no -3.93 is not correct

cwrw238 · Answer

you need to use the quadratic formula to solve this - or if you have a graphic calculator it will do it for you

cwrw238 · Answer

to get -3.83 you must have used 144 not 144t

cwrw238 · Answer

* -3.93

cwrw238 · Answer

that will give you the 2 times

cwrw238 · Answer

the lower value will give the time as it is climbing and the higher the time on the way back down

anonymous · Answer

I'm getting confused lol

cwrw238 · Answer

sorry  you need to  use your calculator to find  t ( 2 values)

cwrw238 · Answer

I'll try to draw it

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