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IGCSE Functions watch

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)

How do I go about this? (the box represents a symbol I-> )

not the first two
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->
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
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?
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)
12. thanks very much

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