Question

Help! giving out medals and will fan!

A firecracker shoots up from a hill 145 feet high with an initial speed of 80 feet per second. Using the formula H(t) = -16t2 + vt + s, approximately how long will it take the firecracker to hit the ground?

13 seconds

11 seconds

Nine seconds

Six seconds

Answer 1

six seconds

Answer 2

Thanks! how'd you get that?

Answer 3

0 = -16t^2+80t+145
Use the quadratic formula.
t = 6.4 seconds

Answer 4

was it correct

Answer 5

yeah :) thanks!

Answer 6

Can you help me with one more?

Answer 7

sure

Answer 8

Function 1
is the graph

Function 2

f(x) = -x^2 + 2x - 15

Function ____ has the larger maximum.
(Put 1 or 2 in the blank space)

Numerical Answers Expected

Answer 9

im not sure but i would like a medal

Answer 10

the maximum of f(x) is when its derivative d(f(x))/dx = 0

take the derivative of f(x). set it equal to 0 and solve for x. replace that value back into f(x) to get the maximum. look at the graph too see if that value is higher or lower

Answer 11

So what would it be? I'm not really sure

Answer 12

@JamesWolf

Answer 13

f(x) = -x^2 + 2x - 15

derivative = -2x + 2 -15

maximum when this = 0

0 = -2x +2 -15
2x = -13
x(max) = -13/2

put this back into the original. and find the value of f(x) at the maximum x
the graphs maximum looks to be around 1. is f(-13/2) bigger or smaller than 1?

Answer 14

smaller?

Answer 15

if thats what it is then thats what it is. idk I havnt put it back into the function f(x)