An arrow shot into the air is 144t-4.9t squared meters above the ground t seconds after it is released

squared-meters
period-of-time

#1

an arrow shot into the air is 144t-4.9t squared meters above the ground t seconds after it is released. during what period of time is the arrow above 100 meters?

Answer:

f(t)= 144t-4.9t^2
100=144t-4.9t^2
4.9t^2-144t+100=0
by quadratic formula
x= (-b+sq.root(b^2-4ac))/2a
x=(144sq.root(144^2-44.9100))/2*4.9
x= 28.7 seconds -> answer