On p. 34 of Schaum's Outline, Calculus, Frank Ayres, problem 40 gives the derivative of of f(x)=(x-1/x=1)^1/2 as I/(x=1)(x^2-1)^1/2.

I get as far as ((x-1/x=1)^-1/2)/(x=1)^2 but cannot reduce it to the answer given. Can someone help.

Thanks

MMH