Question

Given the function f described by f(x) =9x, find each of the following:
(a) f(-2)
(b) f(4)
(c) f(26)

Answer would be f(-2) = ??

Answer 1

f(x) means function of a variable x.
f(-2) means function of -2. so substitute x = -2 in the expression and find the value of f(x)

Answer 2

So...
f(-2)=9*(-2)
f(4)=9*4
f(26)=9*26

Just simplify the right side of those equations and there are your answers :)

Answer 3

I don't know how to do that. It is just so confusing for me.

Answer 4

okay f(x) = 9x means f(x) is function of x such that for a given value of x, the value of the function is 9 times that value of x.
so f(-2) means the value of the function at x = -2
so that is 9 times -2 = -18.

Answer 5

so f(-2) = 9?

Answer 6

No, f(-2)=9*(-2), or -18

Similarly, f(4)=9*4, or 36.

Answer 7

read what I posted.

Answer 8

I am sorry I am so stupid. That's why I am "dumbunny". So f(-2) = 36?

Answer 9

no. read what I posted. f(-2) is 9 times -2 = -18.
the function takes a value x and multiplies it by 9. that is all it does.
so the function is like a magnifying glass. you put an ant on one side of the glass and it appears 9 times larger at the other end.

Answer 10

so if you put 4 at one end, it makes it 9 times larger, that is, it makes it appear as 36.
so f(4) = 36.

Answer 11

so f(-2) = 18 or -18? Right?

Answer 12

no. f(-2) = -18, not +18

Answer 13

no...18

Answer 14

so it would be -18 then

Answer 15

That was right. thank you. So how about
if f(4)=??

Answer 16

yes. do you get what a function is?
suppose you have
f(x) = x+3
what this function f(x) does is,
takes a variable x and adds 3 to it.
so if you have x = 2
f(x) = take 2 and add 3 to it.
that is,
f(x) = 2 +3 = 5
get it?
function means just that. perform some function on an input and give an output.

Answer 17

so f(x) = 9x
means
take a variable x and multiply it by 9.
so f(4) means take 4 and multiply it by 9.

Answer 18

NO, unfortunately I don't get this at all. I am a psych major and algebra is not my forte...

Answer 19

f(4)=?

Answer 20

36?

Answer 21

36 was right...how about f(26) =?

Answer 22

I am getting there.

Answer 23

write f(26) as a sentence in plain english the same way I wrote it for f(4)

Answer 24

so would it be 4 x 26?

Answer 25

or 9 x 26?

Answer 26

you tell me.

Answer 27

first write it in plain english. what does the function f(x) do?

Answer 28

Oh don't tease me...

Answer 29

I think it would be 9 x 26

Answer 30

okay. why do you think that?

Answer 31

I don't know. Because it makes more sense?

Answer 32

why does it make more sense? Did you read what I posted about this function.
what does the function f(x) = 9x do?
it takes a variable x and _______ ?

Answer 33

4 x 26 makes more sense now that I think about it.

Answer 34

why? can you stop guessing and actually read what I posted earlier? It is better to understand what is going on than to guess.

Answer 35

I do not get functions at all.

Answer 36

did you read what I posted or not? Simple question. yes or no?

Answer 37

I am sorry, I just do not get it. That is why I am guessing.

Answer 38

yes. do you get what a function is?
suppose you have
f(x) = x+3
what this function f(x) does is,
takes a variable x and adds 3 to it.
so if you have x = 2
f(x) = take 2 and add 3 to it.
that is,
f(x) = 2 +3 = 5
get it?

Answer 39

YES, I did read what you posted. I just don't understand it.

Answer 40

okay. now we are getting somewhere. What do you not understand about it?

Answer 41

Pretty much the whole concept. It just seems to go right over my head.

Answer 42

Give me psych, biology, history, etc., and I can run circles around anyone, but when it comes to algebra I am a complete moron.

Answer 43

http://www.twiddla.com/579395
join me there.
I will explain the concept.

Answer 44

unless you don't want to learn it. let me know either way.

Answer 45

hello? are you there? I do not want to be wasting my time if you are not interested in the answer. so let me know.

Answer 46

Yes I am here..sorry, had to let my dog out