Question

(ALGEBRA 1) A ball is thrown upward from the top of a building. The function below shows the height of the ball above the ground, f(t), in feet, at different times (t) in seconds:

f(t) = -16t2 + 32t + 90

The average rate of change of f(x) from x = 4 to x = 6 is

Answer 1

like finding the slope of the line
compute
\[\frac{f(6)-f(4)}{6-4}\]

Answer 2

clear how to compute \(f(6)\) etc?

Answer 3

no...

Answer 4

k then lets go slow

Answer 5

\[f(t) = -16t^2 + 32t + 90\]\[f(6)=-16(6^2)+32\times 6+90\]

Answer 6

i would use a calculator
lets try it

Answer 7

wait a sec
i get a negative number
do you?

Answer 8

im so confused.

Answer 9

me too
when you evaluate the function at \(t=6\) you seem to get a negative number
normally that is not a problem, but in this equation \(f(t)\) is supposed to be the height, which cannot be negative

Answer 10

i would say that the question makes no sense, because when the ball hits the ground, it stops

Answer 11

So what do you think the answer is?

Answer 12

we can write an answer, but it will make no sense
but if you need an answer we can find one

Answer 13

sorry i meant \[f(6)=-16(6^2)+32\times 6+90=-294\]

Answer 14

\[f(4)=-16(4)^2+32\times 4+90=-38\]

Answer 15

\[f(6)-f(4)=-294+38=-256\]

Answer 16

\[\frac{f(6)-f(4)}{6-4}=\frac{-256}{2}=-128\]

Answer 17

that is the answer
it makes no sense, but that is the answer

Answer 18

the real answer is that at \(3.6\) seconds the ball hits the ground, and goes no lower

Answer 19

So the rate of change from x=4 to x=6 would be what

Answer 20

@satellite73