# find the inverse of a function

• Oct 2nd 2011, 01:05 PM
Taurus3
find the inverse of a function
it's given that f(x) = v^5 + v^3 + v. So I need to find inverse of (3) and f(f inverse of 2).
I figured out the first, which is relatively easy.
v^5 + v^3 + v = 3, where i get v = 1. So inverse of (3) is 1.

But how do I go about the second part? I know that first I should find the inverse of (2) and then find f(x).
• Oct 2nd 2011, 01:29 PM
mr fantastic
Re: find the inverse of a function
Quote:

Originally Posted by Taurus3
it's given that f(x) = v^5 + v^3 + v. So I need to find inverse of (3) and f(f inverse of 2).
I figured out the first, which is relatively easy.
v^5 + v^3 + v = 3, where i get v = 1. So inverse of (3) is 1.

But how do I go about the second part? I know that first I should find the inverse of (2) and then find f(x).

You're expecetd to know that \$\displaystyle f(f^{-1}(x)) = x\$ by definition.
• Oct 2nd 2011, 01:33 PM
Taurus3
Re: find the inverse of a function
huh? But isn't that just the definition?
• Oct 2nd 2011, 01:39 PM
Siron
Re: find the inverse of a function
Yes and that's exactly what you need, \$\displaystyle f(f^{-1}(2))=...\$?