Let f(x) = y
y = 2^x
x = 2^y
Solve for y.
ln x = ln(2^y)
ln x = y ln 2
ln x/ln 2 = y
Replace y with f^(-1) x.
f^(-1) x = ln x/ln 2
We now know f(x) and f^(-1) x.
Use your graphing calculator to graph the function and its inverse on the same xy-plane. If you don't have a graphing calculator, use DESMOS online.
Good luck.