you will need to find the vertex of this parabola, a) and c) can then be answered
the t of the vertex is -b/(2a)
= -64/-32 = 2
s(2) -16(4) + 64(2) + 80 = 144
the vertex is (2,144), what does that vertex tell you?
b) when it reaches the ground, s = 0
-16t^2 + 64t + 80 = 0
divide be -16
t^2 - 4t - 5 = 0
(t-5)(t+1) = 0
t = 5 or t is a negative
it will 5 seconds to hit the ground
A person standing close to the edge on the top of an 80-foot tower throws a ball with an initial speed of 64 feet per second. After t seconds, the height of the ball above the ground is
s(t) = -16t2 +64t + 80
a. After how many seconds will the ball reach its maximum height?
b. How long will it take before the ball reaches the ground?
c. What is the maximum height of the ball?
1 answer
1 answer