Posted by A.J. on Saturday, November 21, 2009 at 5:08pm.
Please help if you can.
If a ball is shot projected straight upward at a rate of 64 feet per second from a rooftop, 80 feet above ground level, the height of feet above ground is modeled by the equation,
h(t)=16t^2+64t+80
Find h(0), h(1),h(2)
Use the zerofactor property to determine how many seconds it will take for the ball to reach the ground? (What value of t makes h(t)=0)

Math  Reiny, Saturday, November 21, 2009 at 7:39pm
I will do one of them, you do the rest following my method, ok?
f(1) = 16(1)^2 + 64(1) + 80
= 16 + 64 + 80
= 128
when h = 0
16t^2+64t+80 = 0
divide by 16
t^2  4t  5 = 0
(t5)(t+1) = 0
so t=5 or t=1
clearly t > 0 ,so after 5 seconds it will reach the ground.

Math  A.J., Saturday, November 21, 2009 at 8:00pm
Thank you so much. You really helped me understand. I can definitely finish the rest.
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