se  us  dk 

Math forum

Welcome Guest Search | Active Topics | Log In | Register

help with problem Options
Previous Topic · Next Topic
dardar72
#1 Posted : Sunday, June 24, 2012 10:02:13 PM
Rank: Newbie

Groups: Registered Users

Joined: 6/24/2012
Posts: 1

consider the funcations f(x)=x^3-3 and g(x)=3/x+3  what is f(g(x))?
Back to top
 Report Abusive | Report SPAM
lisa
#2 Posted : Tuesday, June 26, 2012 2:26:56 PM
Rank: Administration

Groups: Administration , Administrators, Member, Registered Users

Joined: 3/16/2011
Posts: 33

[dardar72 wrote:]

consider the funcations f(x)=x^3-3 and g(x)=3/x+3  what is f(g(x))?

 

Hi!

 

I guess that your functions are the following

\\f(x)=x^{3}-3\\\\g(x)=\frac{3}{x}+3\\

The function

f(g(x)) tells us that we want to replace all the x:es with the expression for g(x)

f(g(x))=\left ( \frac{3}{x}+3 \right )^{3}-3\\

From here you just have to simplify the expression to its simplest form

\\f(g(x))=\left ( \frac{3}{x}+3 \right )^{3}-3\\\\\\=\left ( \frac{3}{x}+3 \right )\left ( \frac{3}{x}+3 \right )^{2}-3\\\\\\=\left ( \frac{3}{x}+3 \right )\left ( \frac{9}{x^{2}}+\frac{18}{x}+9 \right )-3\\\\\\=\frac{27}{x^{3}}+\frac{27}{x^{2}}+\frac{54}{x^{2}}+\frac{54}{x}+\frac{27}{x}+27-3\\\\\\=\frac{27}{x^{3}}+\frac{81}{x^{2}}+\frac{81}{x}+24\\
Back to top
 Report Abusive | Report SPAM
Users browsing this topic
Guest
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

YAFPro Theme Created by Jaben Cargman (Tiny Gecko)
Powered by YAF 1.9.3 RC2 | YAF © 2003-2008, Yet Another Forum.NET
This page was generated in 0.061 seconds.