Jian17
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For this question:

https://gyazo.com/5e1768cf90d1d5a15eb9a2b7120a039d

I'm getting for the first part ( which is the one I'm having problem with) the domain of f to be x>- (bigger or equal don't know how to put the line under >) -5/2.

Mark scheme says its -9/4.

My question is how do you obtain the domain then after finding the inverse of the inverse function?

I do 2x+5= 0
2x = -5
x = -5/2

Can someone tell me how you obtain -9/4 and the method you would always use? Please
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simon0
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From the diagram, the function  f^{-1}(x) maps  (0,2] to  [f^{-1}(2), \infty).

What is  f^{-1}(2) ?

Then after, can you come up with what  f(x) is?
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RDKGames
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(Original post by Jian17)
For this question:

https://gyazo.com/5e1768cf90d1d5a15eb9a2b7120a039d

I'm getting for the first part ( which is the one I'm having problem with) the domain of f to be x>- (bigger or equal don't know how to put the line under > -5/2.

Mark scheme says its -9/4.

My question is how do you obtain the domain then after finding the inverse of the inverse function?

I do 2x+5= 0
2x = -5
x = -5/2

Can someone tell me how you obtain -9/4 and the method you would always use? Please
Domain of f is the range of f^{-1}

Range of f is the domain of f^{-1}

Applying to your question, you want the domain of f, which is the range of f^{-1}. So, what is the range of f^{-1}(x)=\frac{1-5x}{2x}? Note that 0<x \leq 2.
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