Question

Help please!
A toy rocket was launched from the ground. The function f(x) = -16x2 + 256x shows the height of the rocket f(x), in feet, from the ground at time x seconds.
What is the axis of symmetry of the graph of f(x) and what does it represent? (3 points)

Answer 1

x = 8; it takes 8 seconds to reach the maximum height and 8 seconds to fall back to the ground

x = 16; it takes 16 seconds to reach the maximum height and 16 seconds to fall back to the ground

x = 8; it takes 8 seconds to reach the maximum height and 16 seconds to fall back to the ground

x = 16, it takes 16 seconds to reach the maximum height and 32 seconds to fall back to the ground

Answer 2

@mathway

Answer 3

Alright well we see this is an upside down parabola...

lets find the vertex (where it changes direction)

−b2a=−1282(−16)=12832=4
so the 'x' coordinate of our vertex is 4...

so I'm going to say the rocket would take 4 seconds to get up to maximum height...and then it will fall back down taking 4 seconds

How do i know it will only take 4 seconds to get down? Well I would find out the x-intercepts of the parabola by factoring

-16x^2 + 128x = 0
factor our like terms
-16x(x - 8) = 0

so we have 2 equations

-16x = 0
and
(x - 8) = 0

well that means our 2 x intercepts are 0 and 8

So if it take 4 seconds to go up to the max height...we only have 4 seconds to fall back down

Hence the answer being B

Answer 4

thank you!!!

Answer 5

your welcome! :)

Answer 6

bc i wasnt sure how to find it

Answer 7

my sister had the same question yesterday so her answer was b but im not sure which answer choice is 4 for you lol :D

Answer 8

okay i may need help again late

Answer 9

ok feel free to tag me :)