# Continuity And Differentiability Class 12 Maths

A real valued function is continuous at a point in its domain if the limit of the function at that point equals the value of the function at that point. A function is continuous if it is continuous on the whole of its domain.

Sum, difference, product and quotient of continuous functions are continuous. i.e., if f and g are continuous functions, then

(f ± g) (x) = f(x) ± g(x) is continuous.

(f . g) (x) = f(x) . g (x) is continuous.

\left( \frac{f}{g} \right)(x) = \frac{f(x)}{g(x)} ( {\rm wherever } g(x) \ne 0 ) is continuous.

Every differentiable function is continuous, but the converse is not true.

Chain rule is rule to differentiate composites of functions.

Logarithmic differentiation is a powerful technique to differentiate functions of the form f(x) = [u (x)]^{v (x)} . Here both f(x) and u(x) need to be positive for this technique to make sense.

## Lecture - 1

Topics Discussed in this lecture: How to check continuity and discontinuity in a graph of a function through limits. NCERT Exercise 5.1 (Q6 to Q25)

## Lecture - 2

NCERT Exercise 5.1 (Q26 to Q30)

## Lecture - 3

Extra (HOTS) Questions on Continuity of Functions

## Lecture - 5

NCERT Exercise 5.2 (Q1 to Q8)

Explicit and Implicit functions

NCERT Exercise 5.3 (Q1 to Q15)

Derivative of inverse trigonometric functions

Example 26 and Example 27

## Lecture - 6

NCERT Exercise 5.4 (Q1 to Q10)

Logarithmic Differentiation

NCERT Exercise 5.5 (Q1 to Q3)

## Lecture - 9

What are parametric functions and how to find their derivatives

NCERT Exercise 5.6 (Q1 to Q11)

## Lecture - 10

Second order derivatives or double derivative

NCERT Exercise 5.7 (Q1 to Q17)