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# I don’t understand what they did here... (C3 functions) watch

1. Could you please have a look at part c?

Attachment 698186698188

Why did they make f(x) = x??
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2. Because f-1(x) is a reflection of f(x) in the line y = x
3. For functions of one variable the graph of an inverse function of a function is the graph of y=f(x) reflected in the line y=x and so if the curves touch at any points then they must touch on the line y=x and so f(x)=x and also f^(-1)(x)=x.
4. (Original post by B_9710)
For functions of one variable the graph of an inverse function of a function is the graph of y=f(x) reflected in the line y=x and so if the curves touch at any points then they must touch on the line y=x and so f(x)=x and also f^(-1)(x)=x.
Ah I understand now. Thank you for explaining!

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