Question 34348
Well, you have the right idea but your algebra was a little off!

{{{f(x) = (4/x)+1}}}
{{{y = (4/x)+1}}} Exchange the x and y and solve for x.
{{{x = (4/y)+1}}} Subtract 1 from both sides.
{{{x-1 =4/y}}} Multiply both sides by y.
{{{y(x-1) = 4}}} Finally, divide both sides by x-1
{{{y = 4/(x-1)}}}

{{{f^(-1)*(x) = 4/(x-1)}}} Note! x = 1 not allowed.