The inverse of the function `f: Rvec{x in R : x lt1}` given by `f(x)=(e^x-e^(-x))/(e^x+e^(-x)

given by `f(x)=(e^x-e^(-x))/(e^x+e^(-x)),`
is
`1/2log(1+x)/(1-x)`
(b) `1/2log(2+x)/(2-x)`

`1/2log(1-x)/(1+x)`
(d) None of these