This session is about differentiation of parametric functions, logarithmic differentiation, second order differentiation and nature of function. Definition of differentiability has already been discussed int last session. In this session we will learn ways to find differentiability of functions. L'hospital rule, one of most used concepts, is covered. After that Rolle's theorem and Lagrange's mean value theorem will be covered. These theorem are very fundamentals of differential calculus and are used almost everywhere.