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# Maths Function Help watch

1. I have been struggling with this question. I do know how to do inverse function but I think the x>3 throws me off. I got up to 0=x^2>1 which seems very wrong.
2. (Original post by MainlyMathsHelp)
I have been struggling with this question. I do know how to do inverse function but I think the x>3 throws me off. I got up to 0=x^2>1 which seems very wrong.
Find g inverse and set equal to f. Then solve for x and it should become clear why the x>3 is relevant.
3. (Original post by SherlockHolmes)
Find g inverse and set equal to f. Then solve for x and it should become clear why the x>3 is relevant.
I did that and got 0 = 2x^2 - 20. I tried substituting x >3 into x and that got me to 0=2x^2 > 18 - 20 which got me to 0 = x^2 > -1
4. (Original post by MainlyMathsHelp)
I did that and got 0 = 2x^2 - 20. I tried substituting x >3 into x and that got me to 0=2x^2 > 18 - 20 which got me to 0 = x^2 > -1
Therefore:

Now use difference of two squares.
5. (Original post by SherlockHolmes)
Therefore:

Now use difference of two squares.
Oh of course. I went down the route of substituting x with x>3 which meant I got lost. The exact value of x is root 10. Thank you!

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