## 2002 winter diet, paper 1, Q9a

### Azie

Posted 13 May 2007 - 05:48 PM

The question is: "The function f, defined on a suitable domain is given by f(x) = 3/(x+1). Find an expression for h(x) where h(x) = f(f(x))." i managed 2 do the 1st step so that h(x) = f(3/x+1) but then wat do i do? :s

### xClairex

Posted 13 May 2007 - 06:07 PM

sorry i dont no hw to use latex so it might look a bit messy hopefully you can understand what im meaning though

3/(3/x+1) + 1
= 3/(3+x+1)/(x+1)
=3/(x+4)/(x+1)

= 3/1 * (x+1)/(x+4)

= 3(x+1)/(x+4)

### Azie

Posted 13 May 2007 - 06:17 PM

no, i still dnt really understand it

### xClairex

Posted 13 May 2007 - 06:27 PM

can u do the normal f(g(x)) questions ?

### Pete

Posted 13 May 2007 - 06:30 PM

QUOTE(xClairex @ May 13 2007, 07:07 PM)
sorry i dont no hw to use latex so it might look a bit messy hopefully you can understand what im meaning though

You may want to read up on how uto use LaTeX, then. It's surprisingly easy to get used to

### Azie

Posted 13 May 2007 - 06:30 PM

yeah, most of them, but this 1 is really annoyin me, an im a really superstitious person an all of that so i believe that a question similar 2 it will cum up in the exam if i dnt solve it jus now

### Azie

Posted 13 May 2007 - 06:39 PM

i tried readin up on it but it looks 2 complicated 2 me ...ok, this mite sound like a really stupid question but how did u get the last line?

### Allan_r_123

Posted 13 May 2007 - 07:16 PM

I think the last line is the one that causes confusion, as I have a bit of bother with it myself ;P

### xClairex

Posted 13 May 2007 - 07:22 PM

so you get it up until the last line ye?

### Azie

Posted 13 May 2007 - 07:26 PM

yeah kinda, i definately get up 2 h(x) = f(3/x+1) but then its from there that i get stuck an dnt no what 2 do ...i kinda understand the next line now, not that id ever think of it without being shown it, but the last line totally confuses me :s

### xClairex

Posted 13 May 2007 - 07:39 PM

do you understand where i get [display] times [/display] from ?

### xClairex

Posted 13 May 2007 - 07:44 PM

10;\begin{align*}$$\frac{3}{1}$$ times $$\frac{x+1}{x+4}$$\end{align*} ' alt=' \begin{align*}$$\frac{3}{1}$$ times $$\frac{x+1}{x+4}$$\end{align*} ' align=absmiddle>otetop'>QUOTE(xClairex @ May 13 2007, 08:39 PM)
[display] times [/display]

do you understand where i get [display] times [/display] from ?

i cant get the first line to go away so just ignore that.latex is far too complicated for me

### Azie

Posted 13 May 2007 - 07:52 PM

nope ...i told u i was slow, i bet its really simple as well but i dunno y i cant get it or y i cant c how u got that :s

### xClairex

Posted 13 May 2007 - 08:23 PM

add me on msn maybe it will be easier if i use the handwriting tool that way i can draw arrows etc on and maybe explain better
its ok im slow at times as well i was really confused with this question before dont worry about it