According to traditional mathematics, the derivative of a function at one of its points “Xo” is infinitesimally equivalent to the incremental ratio [f(Xo + h) – f(Xo)] / h with “h” meaning “Delta x”, or in other words,  the difference between the abscissa of the upper extremity, in direction x of thesegment of dimension “h”, constructed … Continua a leggere Differentiation: math definition, derivative rules, formulas, basic principles and graphic meaning