What is the insverse of the function f(x) =2x+1?

F(x) = 2x + 1

To find the inverse of a function you just need to switch the x by y or vice-versa:

-> y = 2x + 1
-> x = 2y + 1

After that you isolate the y again:

-> 2y = x - 1

-> y = (x-1)/2
-> f^-1 (x) = (x-1)/2