Class 11 Maths - KERALA

Relations and Functions

The chapter Relations and Functions in Class 11 Mathematics under the Kerala SCERT syllabus builds the foundation for advanced calculus and algebra. Students learn how to pair elements from two sets using Cartesian products, understand the formal definition of a relation, and master the concept of functions as special types of relations. Key topics include domain, co-domain, range, and various types of real-valued functions along with their graphical representations. This chapter is vital for the Higher Secondary Board Examinations, frequently appearing in both short-answer and essay sections, and forms the core of mathematical reasoning required for engineering and science entrance exams.

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Key Concepts

Cartesian Product of Sets

The set of all ordered pairs (a, b) such that a belongs to set A and b belongs to set B, denoted as A × B.

Relation

A subset of the Cartesian product A × B that establishes a connection between the first and second elements of the ordered pairs.

Function

A special relation from set A to set B where every element in set A has one and only one image in set B.

Domain, Co-domain, and Range

Domain is the set of all inputs, co-domain is the entire target set, and range is the set of actual outputs of a function.

Real-Valued Functions

Functions whose domain and range are subsets of the set of real numbers, including polynomial, rational, modulus, and signum functions.

Important Formulas

n(A × B) = n(A) × n(B)
Total number of relations from set A to set B = 2^(n(A) × n(B))
Domain of (f + g)(x) = Domain of f ∩ Domain of g
Algebra of real functions: (f + g)(x) = f(x) + g(x)

Board Exam Info

In the Kerala (SCERT) Class 11 Mathematics board examination, this chapter typically carries around 6 to 8 marks. Questions usually include finding the Cartesian product, determining the domain and range of given functions, finding types of relations, and sketching graphs of standard real functions.

Frequently Asked Questions

What is the difference between a relation and a function?

Every function is a relation, but not every relation is a function. In a function, each input has a unique output, whereas a relation can map one input to multiple outputs.

How do I find the domain and range of a rational function?

To find the domain, set the denominator not equal to zero and solve for x. To find the range, express x in terms of y and find the valid real values for y.

Why do we study Cartesian products?

Cartesian products provide the universal set of all possible ordered pairs, which is the foundational building block for defining both relations and functions.

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