# Find the functions and their domains.

• Jan 20th 2013, 09:03 PM
Oldspice1212
Find the functions and their domains.
f(x) = x + 1/x , g(x) = x+17/x+2

a) (f o g)(x)

b) (g o f)(x)

c) (f o f)(x)

d) (g o g)(x)

and domains for all...which I think is the hardest part.

So I'm not sure if this is right but let me know if I'm doing it wrong.

For the functions for example a) I would put F(g(x)), g(x) = 1+17/x+2 therefore f(x+17/x+2) = (x+1/x +17/ x+1/x + 2)...and domain I'm not sure what to write other then it can't be divided by 0 but I need to be sure if the function is correct before I can find the domain. THANKS.

Interval notation for domain.

EDIT: Sorry I put it in the wrong section, :X
• Jan 21st 2013, 12:51 AM
chiro
Re: Find the functions and their domains.
Hey Oldspice1212.

Can you show us what you have tried?

(Hint: For what values of x do the intermediate and final composed functions exist)?
• Jan 21st 2013, 01:18 PM
Oldspice1212
Re: Find the functions and their domains.
Quote:

Originally Posted by chiro

(Hint: For what values of x do the intermediate and final composed functions exist)?

I'll be honest I'm not quite sure what that even means lol but on my first post that was my attempt on part a) so yeah I just need to know if that's right then I can figure out the rest.
• Jan 21st 2013, 01:29 PM
chiro
Re: Find the functions and their domains.
Basically what I mean is that if you have a function, then what values of x make the function spit out a real number (no infinities for example) for the functions in your question?
• Jan 21st 2013, 01:33 PM
HallsofIvy
Re: Find the functions and their domains.
Use parentheses! Do you mean (x+ 1)/x or x+ 1/x? Do you mean 1+(17x/x)+ 2 or (1+17x)/(x+ 2)?
• Jan 21st 2013, 08:37 PM
Oldspice1212
Re: Find the functions and their domains.
Well actually (x + 1/x +17)/(x+1/x+2) this is one bracket but doing it this way makes it easier for you to tell what I did lol, but this seems wrong...:S

I put function f everywhere x is on function g. :X
• Jan 21st 2013, 09:24 PM
Oldspice1212
Re: Find the functions and their domains.
I got it ^.^