Question

I really need help with my take home test. The problem is f(x)=(x-7)/2, what is the value of (f°f^-1)(3). Really struggled with this one. Options are:
1) 2x+7

2)-2

3) 3

4) x

Answer 1

3) 3 is the answer to this equation

Answer 2

Answer: 3) 3
First,We can find the inverse function of f(x) which is f^-1(x);
Let f(x)=y , x=f^-1(y)
(x-7)/2=y
(x-7)=2y
x=2y+7
Subtitute this equation x=2y+7 in the equation f^-1(y) and we have;
f^-1(y)=2y+7
change y into x,
f^-1(x)=2x+7

(f°f^-1)(3)=(f×(f^-1)(3))
=f(2×(3)+7)
=f(6+7)
=f(13)
=(13-7)/2
=6/2
=3
Hope this helps and sorry if my answer is wrong.