# IGCSE FunctionsWatch

#1
f : x I-> 2x – 1
g : x I-> , x ≠ 0

(a) Find the value of
(i) f(3),
...............................
(ii) fg(6).
...............................
(b) Express the inverse function f –1 in the form f –1: x �� ...
.............................
(c) (i) Express the composite function gf in the form gf : x �� ...
...............................
(ii) Which value of x must be excluded from the domain of gf ?
x = ........................
(2)

not the first two
10 years ago
#2
Well, what have you done yourself?
#3
I can understand the first two, but I am confused with the symbol I->. Does it mean the same thing as an equals sign?

I can do the exclusion one provided I can do the others. We have always used = rather than I->
10 years ago
#4
It roughly means "maps to". For example, means that the function f takes a value x and outputs a value of (2x-1). An alternative notation for this is
#5
Thanks! Ill relay back the answer and it would be great if you could check it!
#6
ok here goes:

a) 5
ii) 0
b) (x+1)/2
c) 3/(2x-1)
ii) 1/2
10 years ago
#7
Well, you haven't told us what g is, but your answers to a)i. and b) are correct.
#8
what do you mean?
10 years ago
#9
In your first post, you haven't told us what the function g is. This, combined with my lack of supernatural powers, means I cannot check the rest of your answers.
#10
oh i am extremely sorry

g(x)= 3/x (and cannot equal 0 for obvious reasons)
10 years ago
#11
0
#12
thanks very much
X

new posts

Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Brunel University London
Wed, 23 Jan '19
• University of the West of England, Bristol
Wed, 23 Jan '19
• University of East London
Wed, 23 Jan '19

### Poll

Join the discussion

#### Are you chained to your phone?

Yes (16)
18.39%
Yes, but I'm trying to cut back (36)
41.38%
Nope, not that interesting (35)
40.23%