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C3 question 6 OCR MEI 2009

Hi. I'm doing a past paper for C3 and I don't understand this question. If ff(x) of a function equals x, how can you conclude that f(x) is equal to its inverse function.
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Pangol
15
Original post by Gaby123
Hi. I'm doing a past paper for C3 and I don't understand this question. If ff(x) of a function equals x, how can you conclude that f(x) is equal to its inverse function.


Start with what you have got, ff(x) = x (or, more clearly, f(f(x)) = x), and then apply f inverse to both sides.
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Gaby123
OP
6
Original post by Pangol
Start with what you have got, ff(x) = x (or, more clearly, f(f(x)) = x), and then apply f inverse to both sides.

Thanks for your reply:smile:
How do you apply f inverse?
Original post by Gaby123
Thanks for your reply:smile:
How do you apply f inverse?


to get inverse f(x) then swap the x and y's around and rearrange to have y as the subject
Reply 4
Avatar for Pangol
Pangol
15
By "apply f inverse", I mean take f inverse of both sides. So, do f inverse to the left hand side and to the right hand side. The right hand side will then be f^(-1)(x).

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