The inverse function is f(x) =

You can find the inverse of any function by switching the f(x) value and the x value. Then solve for the new f(x) value. The result will be your inverse function. Below is the step-by-step process for solving this one.
f(x) = 2x + 1 ---> Switch the f(x) and x values
x = 2f(x) + 1 ---> Subtract 1 from both sides
x - 1 = 2f(x) ----> Divide each side by 2.
= f(x) ---> Switch the order so that it looks like a function.
f(x) =

And that would be your inverse function.