The function \(\mathrm f\) is defined by

\(\mathrm f(x)=\frac1{2x-5},\qquad x\gt2.5.\)

(i) Find an expression for \(\mathrm f^{-1}(x)\).

(ii) State the domain of \(\mathrm f^{-1}(x)\).

(iii) Find an expression for \(\mathrm f^2(x)\), giving your answer in the form \(\dfrac{ax+b}{cx+d}\), where \(a\), \(b\), \(c\) and \(d\) are integers to be found.