Question 541823
THe height in feet a ball is t seconds after being throan in the air is given by H(t)=-16t^2+64t+5

A)How long did it take the ball to reach its maximum height above the ground
Vertex of parabola is the max:
t = -b/(2a)
t = -64/(2(-16))
t = -64/(-32)
t = 2 seconds
.
B)What was the maximum height above the ground the ball reached
plug t=2 into:
H(t)=-16t^2+64t+5
H(2)=-16(2)^2+64(2)+5
H(2)=-16(4)+128+5
H(2)=-64+128+5
H(2)= 69 feet