SOLUTION: Find the radius of curvature of function f(x) = x + 1/x at point (1, 2)?

    The radius of curvature of a curve at a point M(x,y) is called the inverse of the curvature K of the curve at this point: 

                  R = 1/K. 


    Hence for plane curves given by the explicit equation y= f(x), the radius of curvature at a point M(x,y) 

    is given by the following expression: 


                  R = ((1+(y′(x))^2)^(3/2)) / |(y′′(x))|.