The height in feet of a toy rocket is modeled by the function y = −16t^2 + 128t, where t is the time in seconds after it is launched. Find the maximum height of the rocket and the time it takes the rocket to reach this height. Then find how long the rocket will be in air.
356 ft; 6 s; 12 s
312 ft; 5 s; 10 s
200 ft; 2 s; 4 s
256 ft; 4 s; 8 s

Question

The height in feet of a toy rocket is modeled by the function y = −16t^2 + 128t, where t is the time in seconds after it is launched. Find the maximum height of the rocket and the time it takes the rocket to reach this height. Then find how long the rocket will be in air.
356 ft; 6 s; 12 s
312 ft; 5 s; 10 s
200 ft; 2 s; 4 s
256 ft; 4 s; 8 s

will.h · Answer

are you sure this is the function y = −16t^2 + 128t?

mackenzie2013 · Answer

Yes

will.h · Answer

you may eliminate both A and B
Why? quite simple if you find the t value (zeros) you would find them lay on (0,0) (8,0)
Do you know how to find the zeros or do you want me to explain?

will.h · Answer

Make sense so far?

mackenzie2013 · Answer

I just need it checked, sorry haha. I chose D.

will.h · Answer

you are right 
Why? the question is about finding the vertex 
and the vertex is about (4,255)

will.h · Answer

-b/2a is a terrific way to find the axis of symmetry and then finding the y values should be easy

will.h · Answer

hope it helps
C ya