Question

Let f(x)=lx^2-35l. Find the average rate of change of f(x) from x=7 to x=4.

Answer 1

i know how to do rate of change but this prob is a little different

Answer 2

average rate of change is the change in f(x) from x1 to x2 divided by the interval size |x1-x2]

Answer 3

ok let me show u what u did:
f(7)=l(7)^2-35l=l49-35l=l14l=14
f(4)=l(4)^2-35l=l16-35l=l-19l=19
and then 19-14 ? ...that's all i had

Answer 4

i mean what I did

Answer 5

my bad

Answer 6

yes @mariomintchev, you are almost there, its:\[(14-19)/3=-5/3\]

Answer 7

why isnt it 19-14

Answer 8

rate of change means "how fast is one value changing with respect to another". e.g. think of instantaneous rate of change - that would be dy/dx

Answer 9

\[(f(7)-f(4))/7-4\]
(14-(-19))/3
33/3
11

Answer 10

where did u guys get the 3 from?

Answer 11

o ok nevermind!

Answer 12

x1-x2

Answer 13

here you are asked for an average rate of change - so it is the change in f(x) divided by the change in x
@ChrisS - I think you missed the "magnitude" operator in f(x)

Answer 14

its positive 19 not -19

Answer 15

right, I see that now.. my bad

Answer 16

also the answer would be -5/4 not -5/3

Answer 17

o nevermind again

Answer 18

:-)

Answer 19

THANKS :)