Question

For the function f(x) = x + 9, find (f o f-1)(5)

Answer 1

A. 4

B. 10

C. 0

D. 6

Answer 2

@IMStuck
@sweetburger
@Lena772

Answer 3

The first thing you have to do is find the inverse function of f(x). To find the inverse function, you swap the x and the y and then solve for y. If f(x) = x + 9, then y = x + 9. The inverse of this is x = y + 9. Then solving for y gives you x - 9 = y. Put 5 in for x here and what do you get?

Answer 4

5-9=-4

Answer 5

@IMStuck

Answer 6

I am getting that the answer is 5 and it is not one of your choices. Let me look into this for a minute, ok?

Answer 7

I don't now what to do with this. if we put x through the function f, then put it through the inverse of f, we end up with x again. In this case, x is 5. So if we put 5 through the inverse of f, and then put that result through f, we come back to 5. Which is what I keep getting. Unless I am misunderstanding what you are posting...

Answer 8

Maybe someone else has a different view of what your question is

Answer 9

Can you recheck the question? Maybe options are from wrong question?

Because inverse functions are defined as \[f(f^{-1}(x)) = f^{-1}(f(x)) = x\]
Composition of function and its inverse is always x. Therefore your answer should be 5.