Class 11 Maths - BIHAR

Relations and Functions

The chapter 'Relations and Functions' in Class 11 Mathematics builds the foundation for advanced algebra and calculus. Students learn how to map elements from one set to another using ordered pairs. We start with Cartesian products of sets, define what a relation is, and then narrow down to a special type of relation called a function. Understanding domains, co-domains, and ranges is crucial. In the Bihar Board (BSEB) examinations, this chapter is fundamental because it forms the base for calculus, trigonometry graphs, and inverse trigonometric functions in Class 12, frequently appearing in both objective and short-answer sections.

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Key Concepts

Cartesian Product of Sets

The Cartesian product of two non-empty sets A and B, denoted by A × B, is the set of all ordered pairs (a, b) such that a ∈ A and b ∈ B.

Relation

A relation R from a set A to a set B is a subset of the Cartesian product A × B, established by a specific rule connecting the elements.

Function

A function is a special type of relation where every element in the domain (set A) has one and only one image in the co-domain (set B).

Domain, Co-domain, and Range

The domain is the set of all possible inputs, the co-domain is the entire target set, and the range is the set of all actual output values produced by the function.

Algebra of Real Functions

Real-valued functions can be added, subtracted, multiplied, and divided pointwise, much like ordinary numbers under specific domain restrictions.

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 = Domain of f ∩ Domain of g
(f / g)(x) = f(x) / g(x), provided g(x) ≠ 0

Board Exam Info

In the Bihar (BSEB) Class 11 Mathematics examination, Relations and Functions typically carries around 6 to 10 marks. Questions commonly include finding the Cartesian product, determining the domain and range of given functions, proving whether a relation is a function, and solving algebra of functions problems in both objective and short-answer formats.

Frequently Asked Questions

What is the main difference between a relation and a function?

Every function is a relation, but not every relation is a function. In a function, each input (domain value) must map to exactly one output, whereas in a relation, one input can map 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 to exclude values that make the function undefined. To find the range, express x in terms of y and find the valid set of values for y.

Why is this chapter important for Class 12?

This chapter is the direct prerequisite for Class 12 chapters like Relations and Functions (advanced types), Inverse Trigonometric Functions, and Limits, Continuity, and Differentiability in Calculus.

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