# Part - 1 Lecture - 5 Chapter 1 Relations and Functions

When you want to succeed as bad as you want to breathe, then you’ll be successful. – **Eric Thomas**

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Lecture 5 Questions from Exercise 1.3, NCERT Exemplar, Board’s Question Bank

Introduction to composite functions

Detailed explanation for composite functions

1. Let *f* :{1, 3, 4} → {1, 2, 5} and *g*:{1, 2, 5} → {1, 3} be given by *f* = {(1, 2), (3, 5), (4, 1)} and *g* = {(1, 3), (2, 3), (5, 1)}. Write down *gof*. (N)

2. If *f* = {(5, 2), (6, 3)}, *g* = {(2, 5), (3, 6)}, write *fog*. (E)

3. If the mappings *f* and *g* are given by *f* = {(1, 2), (3, 5), (4, 1)} and *g* = {(2, 3), (5, 1), (1, 3)}, write *fog*. (E)

4. If *f* : {1, 3} →{1, 2, 5} and *g*: {1, 2, 5} →{1, 2, 3, 4} be given by *f* = {(1, 2), (3, 5)}, *g* = {( 1, 3), (2, 3), (5, 1 )}, write *gof* . (B)