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# Can someone explain functions to me? IGCSE maths?

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1. Can someone explain functions to me? IGCSE maths?
How do you do the inverse of a function? And how do you generally use functions? e.g f (x) and gf(x) ?

Thanks for any help.
2. Re: Can someone explain functions to me? IGCSE maths?
(Original post by taylorswiftx)
How do you do the inverse of a function? And how do you generally use functions? e.g f (x) and gf(x) ?

Thanks for any help.
A function is just a rule for giving a result for each value you give it.

So f(x) = x + 2

means the result of working out f(x) from a starting point of x is obtained by adding 2 to x.

Functions often work on numbers, but don't have to. So you can define:

mother(person) = the obvious person.

The inverse of a function is the function you need to undo the process.

So if f(x) = x + 2

then f^-1(x) = x - 2

Now think about inverting the 'mother' function. If you're an only child, works fine. Trouble is, if you have siblings, you can't invert it.
3. Re: Can someone explain functions to me? IGCSE maths?
Quite. To find an inverse function , set , then rearrange to make the subject, which will get you to , and then you've found and can just replace with .

e.g.

A function of a function works the same way that functions have before, taking , whatever that happens to be, and transforming it in the way that prescribes.

e.g.

etc.

So if
then
and
Last edited by I Am Herenow; 12-05-2012 at 20:59.
4. Re: Can someone explain functions to me? IGCSE maths?
thank you so much

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Last updated: May 13, 2012
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