# Find -f(x)

• Jan 19th 2007, 02:07 PM
symmetry
Find -f(x)
Find -f(x) for:

(a) f(x) = 3 - x

(b) f(x) = 1/x
• Jan 19th 2007, 02:09 PM
CaptainBlack
Quote:

Originally Posted by symmetry
Find -f(x) for:

(a) f(x) = 3 - x

(b) f(x) = 1/x

Are you sure that you have the question right.

As it is it is too trivial to be worth troubling with.

RonL
• Jan 19th 2007, 07:32 PM
symmetry
Ron
Ron,

The question is exactly as appeared in the math book. I'm sure it is another plug and chug, right?

I just get confused by the negative in front of f(x). See it?

What do I do in this case?

Thanks!
• Jan 20th 2007, 04:58 AM
topsquark
Quote:

Originally Posted by symmetry
Ron,

The question is exactly as appeared in the math book. I'm sure it is another plug and chug, right?

I just get confused by the negative in front of f(x). See it?

What do I do in this case?

Thanks!

What does it mean when you have "-3" for example? I think some of the problem here is in the way you are looking at "f(x)." In the context you are looking at it f(x) is just a (probably real) number. So the negative sign is the same as it is in any other context when applied to a number.

-Dan
• Jan 20th 2007, 06:46 AM
symmetry
ok
Let's see:

-f(x) applied in f(x) = 3 - x

Becomes 3 - (-x) = 3 + x, right?

Or, is it - 3 + x?

Or maybe - 3 - x?
• Jan 21st 2007, 05:19 AM
topsquark
Quote:

Originally Posted by symmetry
Let's see:

-f(x) applied in f(x) = 3 - x

Becomes 3 - (-x) = 3 + x, right?

Or, is it - 3 + x?

Or maybe - 3 - x?

No. f(x) = 3 - x means that -f(x) = -(3 - x) = -3 + x.

The "-" in front of the f(x) affects the entire function.

-Dan
• Jan 21st 2007, 05:48 AM
symmetry
ok
Okay...the negative sign in front of the function (-f(x)) affects the whole function.

Now it is very clear.

Thanks!