Question

PLEASE HELP!!!!
A ball is thrown upward from the top of a building. The function below shows the height of the ball in relation to sea level, ft, in feet, at different times t in seconds:

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

The average rate of change of f(t) from t = 4 seconds to t = 6 seconds is _____ feet per second.

Answer 1

Plug in 4 for t and solve for f(t). Then plug in 6 for t and solve again. Then find the average of those two.

Answer 2

f(6) = -16(6)^2 -32(6) +90
-678

f(4)= -16(4)^2 -32(4) +90
-294

Answer 3

Wait, sorry. Ignore the last instruction. To find the rate of change, you'll need to find teh slope of the two points.

Answer 4

You messed up the sign of 32. It's + 32, not - 32

Answer 5

@CountryGurl15 do you understand?

Answer 6

oh sorry, let me fix that =) hold on

Answer 7

f(6)=-16(6)^2 +32(6) +90
-294
f(4)= -16(4)^2 +32(4) +90
-38

Answer 8

@StudyGurl14

Answer 9

The second one is correct, but -294 is not.

Answer 10

hmmm idk how i keep getting that one wrong!

Answer 11

is it 186?

Answer 12

@StudyGurl14

Answer 13

Correct.

Answer 14

Now you have these points: (4, -38) and (6, 186), right? To find the rate of change, find teh slope of these two points.

Answer 15

okay awesome thx so much! =)
can i double check my slope with you once i get it please? =)

Answer 16

Slope is 112 right, @StudyGurl14 =)

Answer 17

Correct. nice job. :)

Answer 18

awesome so that's my answer right?

Answer 19

Yep.

Answer 20

awesome! thx so much =)