Class 11 Maths Chapter 2 Relations and Functions – Revision Notes

Quick revision notes for Class 11 Maths Chapter 2 (Relations and Functions). These Class 11 Maths Chapter 2 notes are ideal for quick revision just before exams.

Cartesian Product

• A×B = all ordered pairs (a,b), a∈A, b∈B. |A×B| = |A|×|B|.

Relations

• Relation = subset of A×B. Domain = first elements; Range = second elements.

Functions

• Special relation: each domain element → exactly one output.

Types of Functions

• Identity: f(x)=x. Constant: f(x)=c. Modulus: f(x)=|x|. Signum: −1/0/1. Greatest integer: [x].

Algebra of Functions

• (f+g)(x), (f−g)(x), (fg)(x), (f/g)(x) [g(x)≠0].

One-Line Summary

A function is a relation where every domain element maps to exactly one output, and functions can be combined algebraically (sum, difference, product, quotient) just like numbers.

Written by Satish

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