I'm assuming that is f(x) = (x-1)/x
In that case, the answer would be just x = 1.
However, if the original is f(x) = x - (1/x) the answer would be x = 1 and x = -1.
It's really just a formatting thing—if the given equation is indeed f(x) = (x-1)/x then x = 1 is the answer.
Hope this helped!! xx