Answer:
The inverse  i.e f^-1 (x) is (x-1)/2
Step-by-step explanation:
The main method for finding inverse function is as follows: 
We let y =f(x), and write the function as y = 2x + 1. 
Next, we swap the x and y, then rearrange to make y the subject. So i.e: 
x = 2y + 1 (just swapping x and y)
x - 1 = 2y
y = (x-1)/2  (solving for x). 
So f^-1 (x) = (x-1)/2