# Function Composition.

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• Dec 8th 2011, 12:53 PM
ht14
Function Composition.
Trying to work out the answer to the following:

Let f1 and f2 be two functions from N to N such that:
f1(x) = x^2 and f2(x) = 3x + 6x^2.

Question 1) What is the function f1 ∘ f2?
Question 2) What is the function f2 ∘ f1?

I am very confused by function composition and any help would be greatly appreciated!

Thanks! :D
• Dec 8th 2011, 01:00 PM
pickslides
Re: Function Composition - help needed!
Replace the whole function for x, so

$f_1(f_2(x)) = (f_2(x))^2 = (3x + 6x^2)^2$

Finish it off.
• Dec 8th 2011, 01:04 PM
ht14
Re: Function Composition
Quote:

Originally Posted by pickslides
Replace the whole function for x, so

$f_1(f_2(x)) = (f_2(x))^2 = (3x + 6x^2)^2$

Finish it off.

Thank You ever so much :)