# Question regarding inverse functions

by michellemich
Tags: functions, inverse
 P: 1 f(x) where x belongs to all real numbers inverse: f-1(x), where x belongs to all real numbers True or False: The inverse of f(x+3) is f-1(x+3) My ideas: I think that it is false given that when you usually find the inverse of a function, you switch the x and y variables and solve for y again meaning that the inverse couldn't stay the same. I figured since the domain and range of f(x) belong to all real numbers, possibly f(x) = x and then inputting f(x+3) = x+ 3 then y = x+3 then y = x - 3 but im not really sure if thats right :s
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 Quote by michellemich f(x) where x belongs to all real numbers inverse: f-1(x), where x belongs to all real numbers True or False: The inverse of f(x+3) is f-1(x+3) My ideas: I think that it is false given that when you usually find the inverse of a function, you switch the x and y variables and solve for y again meaning that the inverse couldn't stay the same. I figured since the domain and range of f(x) belong to all real numbers, possibly f(x) = x and then inputting f(x+3) = x+ 3 then y = x+3 then y = x - 3 but im not really sure if thats right :s
You are given that ##f## has an inverse ##f^{-1}##. What happens when you solve the equation ##y=f(x+3)## for ##x##?
 P: 35 Good Day michellemich! If you are not sure of your answer, try some composition: let your original function be f(x)and your questionable inverse function be g(x) Evaluate (f of g) and (g of f). If they undo each other, they are inverses.
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## Question regarding inverse functions

If you want to know if this is true for all invertible functions, it is simple enough to find a counterexample.

If, say, f(x)= 2x+ 3, then $f(x)= 3x- 2$, then $f^{-1}(x)= (x+ 2)/3$. f(x+3)= 3(x+ 3)- 2= 3x+ 7. The inverse of that function is $(x- 7)/3$. Is that equal to $f^{-1}(x+ 3)= (x+3+ 2)/3= (x+ 5)/3$?

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