Question

May you verify if my answer is correct ?

An object is launched upward at 64 ft/sec from a platform that is 80 feet high. What is the object's maximum height if the equation of height (h) in terms of time (t) of the object is given by h(t) = -16t2 + 64t + 80?
A. 272
B. 144
C. 1232
D. 616

Answer 1

I got B. 144 by plugging in or t, however I'm really not sure.

Answer 2

*for

Answer 3

h(t) = -16t^22 + 64t + 80
is the equation of a parabola.
To find the maximum, you need to find the vertex of the parabola.
The x-coordinate of the vertex occurs at -b / 2a
So it occurs when t = -64 / (2*(-16)) = -64 / -32 = 2 sec.
put t = 2 in h(t) to find the max height.
h(2) = -16(2)^2 + 64(2) + 80
= -64 + 128 + 80 = 144 feet.

Answer 4

correct