sketching functions

**jvignacio** · March 11th 2009, 10:18 PM

hi, when it says to sketch (f o g)(x)

and $f(x) = x^2$ , $g(x) = 4x+3$

is that just $(4x+3)^2$ or $(4x+3)^2 \cdot x$ ?

cheers

**ADARSH** · March 11th 2009, 10:22 PM

Originally Posted by jvignacio

hi, when it says to sketch (f o g)(x)

and $f(x) = x^2$ , $g(x) = 4x+3$

is that just $(4x+3)^2$ or $(4x+3)^2 \cdot x$ ?

cheers

Its just the first one

fog is a fuction like f

When written as fog(x) its similar to writing f(x)

**jvignacio** · March 11th 2009, 11:46 PM

Originally Posted by ADARSH

Its just the first one

fog is a fuction like f

When written as fog(x) its similar to writing f(x)

ahh yeah so we dont multiply (f o g) by x, just leave it as (f o g) , in this case $(4x+3)^2$ correct?

**ADARSH** · March 12th 2009, 01:01 AM

Originally Posted by jvignacio

ahh yeah so we dont multiply (f o g) by x, just leave it as (f o g) , in this case $(4x+3)^2$ correct?

yes it is

(fog)(x) = f(g(x))

**HallsofIvy** · March 12th 2009, 04:23 PM

Originally Posted by jvignacio

ahh yeah so we dont multiply (f o g) by x, just leave it as (f o g) , in this case $(4x+3)^2$ correct?

The notation f(x), with f a function, never means "multiply $f\cdot x$ "!

**jvignacio** · March 12th 2009, 04:35 PM

Originally Posted by HallsofIvy

The notation f(x), with f a function, never means "multiply $f\cdot x$ "!

yeah i know f(x) but i was confused with (f o g)(x) = f(g(x))

Thread: sketching functions