We can compute the derivative of the principal branch of , which is the function  

            .   By the chain rule,  

(5-28)            .  

    If we restrict to the principal branch,  , then Equation (5-28) can be written in the familiar form that you learned in calculus.  That is, for and z not a negative real number,

            .  

Exploration

(c) 2006 John H. Mathews, Russell W. Howell