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f(x)=x-1 g(x)=x^2 solve the equation gf(x)=f^-1 (x)

title says it all

thanks in advance

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

solve the equation gf(x)=f^-1(x)
Reply 1
Original post by getoom
title says it all

thanks in advance

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

solve the equation gf(x)=f^-1(x)


I assume by f^-1 (x) you mean the inverse function of f(x) ? If so I think the following is right...

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

lets say f(x) = y , so y = x-1.
to get the inverse, switch y and x: x =y-1
y = x+1
= f^-1 (x)

g(f(x)) = f^-1 (x)
(x-1)^2 = x + 1
x^2 -2x +1 = x +1
x^2 - 3x = 0
x(x-3) = 0

so x = 0 or x = 3

i hope that helps, do you have the answers? let me know if it is correct
Original post by samar786
I assume by f^-1 (x) you mean the inverse function of f(x) ? If so I think the following is right...

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

lets say f(x) = y , so y = x-1.
to get the inverse, switch y and x: x =y-1
y = x+1
= f^-1 (x)

g(f(x)) = f^-1 (x)
(x-1)^2 = x + 1
x^2 -2x +1 = x +1
x^2 - 3x = 0
x(x-3) = 0

so x = 0 or x = 3

i hope that helps, do you have the answers? let me know if it is correct


that's what i keep getting but my workbook says x^2-1 (without working out a final value of x) and then im like, wat?
Reply 3
Original post by getoom
that's what i keep getting but my workbook says x^2-1 (without working out a final value of x) and then im like, wat?


so it doesnt give you a value of x as the answer even though thats what the question asked? does it just give the answer or any working out?
Original post by samar786
so it doesnt give you a value of x as the answer even though thats what the question asked? does it just give the answer or any working out?


just the answer

the book dosent want a value of x just a simplified final equation ... i fink
Reply 5
Original post by getoom
just the answer

the book dosent want a value of x just a simplified final equation ... i fink


can't think of anything mate, sorry. let me know if you find out
Reply 6
Original post by samar786
... ...


Please do not give full solutions as your first response

The forum guideline suggests hints and support first

Then solutions as a last resort
Original post by getoom
that's what i keep getting but my workbook says x^2-1 (without working out a final value of x) and then im like, wat?


x^2 - 1 would be the answer to fg(x) but otherwise no it's wrong. Make sure you're reading the right answer etc.

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