A football is kicked into the air from an initial height of 4 feet. The height, in feet, of the football above the ground is given by s (t)=-16^2+50t+4, where t is time, in seconds, and t=0. At what time will the football be 25 feet above the ground?
3.625 seconds
3.20 seconds
0.5 seconds or 3.625 seconds
0.5 seconds or 2.625 seconds

Question

A football is kicked into the air from an initial height of 4 feet. The height, in feet, of the football above the ground is given by ￼s (t)=-16^2+50t+4, where t is time, in seconds, and t>=0. At what time will the football be 25 feet above the ground? 
3.625 seconds
3.20 seconds
0.5 seconds or 3.625 seconds
0.5 seconds or 2.625 seconds

agent0smith · Answer

set the height 25 equal to the equation

-16^2+50t+4 = 25
now subtract 25 on both sides

You'll probably want to use the quadratic formula...

agent0smith · Answer

Or... just plug in t values

3.625 seconds
3.20 seconds
0.5 seconds or 3.625 seconds
0.5 seconds or 2.625 seconds

plug each of those into
-16^2+50t+4

and see if you get 25

anonymous · Answer

i would plug it into the first equation??

agent0smith · Answer

yep plug in each of those times into -16^2+50t+4 and if you get 25, there you go

anonymous · Answer

do i plug it in for t?

agent0smith · Answer

yep

agent0smith · Answer

should be -16t^2+50t+4 btw... you missed a t

anonymous · Answer

hah wow..your really smart lol...

anonymous · Answer

when im squaring the -16 am i supposed to put the -16 in parentheses?

agent0smith · Answer

thanks! :D

it's -16t^2+50t+4 so put the time in place of t... like here:

$$\Large -16()^2+50(  ) +4$$put the time in the brackets

anonymous · Answer

ok thats what i thought! lol :P

anonymous · Answer

do you have the answers to this test?

anonymous · Answer

FOr the people who are searching up the problem online and don't want to DO the work. It's 
D. 0.5 seconds.