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  1. Chapter 1 Class 12 Relation and Functions
  2. Serial order wise
  3. Examples

    Example 1

    Example 2

    Example 3

    Example 4 Important

    Example 5

    Example 6 Important

    Example 7

    Example 8

    Example 9

    Example 10

    Example 11 Important

    Example 12 Important

    Example 13 Important

    Example 14 Important

    Example 15 Not in Syllabus - CBSE Exams 2021

    Example 16 Not in Syllabus - CBSE Exams 2021

    Example 17 Not in Syllabus - CBSE Exams 2021

    Example 18 Important Not in Syllabus - CBSE Exams 2021

    Example 19 Important Not in Syllabus - CBSE Exams 2021

    Example 20 Not in Syllabus - CBSE Exams 2021

    Example 21 Not in Syllabus - CBSE Exams 2021

    Example 22 Not in Syllabus - CBSE Exams 2021

    Example 23 Important Not in Syllabus - CBSE Exams 2021

    Example 24 Not in Syllabus - CBSE Exams 2021

    Example 25 Important Not in Syllabus - CBSE Exams 2021

    Example 26 Not in Syllabus - CBSE Exams 2021

    Example 27 Important Not in Syllabus - CBSE Exams 2021

    Example 28 Not in Syllabus - CBSE Exams 2021

    Example 29 Not in Syllabus - CBSE Exams 2021

    Example 30 Not in Syllabus - CBSE Exams 2021

    Example 31 Not in Syllabus - CBSE Exams 2021

    Example 32 Not in Syllabus - CBSE Exams 2021

    Example 33 Not in Syllabus - CBSE Exams 2021

    Example 34 Not in Syllabus - CBSE Exams 2021

    Example 35 Not in Syllabus - CBSE Exams 2021

    Example 36 Not in Syllabus - CBSE Exams 2021

    Example 37 Not in Syllabus - CBSE Exams 2021

    Example 38 Not in Syllabus - CBSE Exams 2021

    Example 39 Not in Syllabus - CBSE Exams 2021

    Example 40 Not in Syllabus - CBSE Exams 2021

    Example 41 Important

    Example 42 Important

    Example 43 Important

    Example 44

    Example 45 Important Not in Syllabus - CBSE Exams 2021

    Example 46 Important

    Example 47 Important

    Example 48 Important

    Example 49

    Example 50

    Example 51 Important You are here


Transcript

Example 51 Consider a function f : [0,π/2 ] → R given by f (x) = sin x and g: [0,π/2 ] → R given by g(x) = cos x. Show that f & g are one-one, but f + g is not Checking one-one for f f : [0, π/2 ] → R f (x) = sin x f(x1) = sin x1 f(x2) = sin x2 Putting f(x1) = f(x2) sin x1 = sin x2 So, x1 = x2 Rough One-one Steps: 1. Calculate f(x1) 2. Calculate f(x2) 3. Putting f(x1) = f(x2) we have to prove x1 = x2 Hence, if f(x1) = f(x2) , then x1 = x2 ∴ f is one-one Checking one-one for g g : [0,π/2 ] → R g(x) = cos x g(x1) = cos x1 g(x2) = cos x2 Putting g(x1) = g(x2) cos x1 = cos x2 So, x1 = x2 Rough One-one Steps: 1. Calculate f(x1) 2. Calculate f(x2) 3. Putting f(x1) = f(x2) we have to prove x1 = x2 Hence, if g(x1) = g(x2) , then x1 = x2 ∴ g is one-one Checking one-one for f + g f + g : [0,π/2 ] → R f + g (x) = sin x + cos x But (f + g) (0) = sin 0 + cos 0 = 0 + 1 = 1 &(f + g) [𝛑/𝟐] = sin π/2 + cos π/2 = 1 + 0 = 1 Since, different elements 0, 𝜋/2 have the same image 1, ∴ f + g is not one-one.

Examples

Example 1

Example 2

Example 3

Example 4 Important

Example 5

Example 6 Important

Example 7

Example 8

Example 9

Example 10

Example 11 Important

Example 12 Important

Example 13 Important

Example 14 Important

Example 15 Not in Syllabus - CBSE Exams 2021

Example 16 Not in Syllabus - CBSE Exams 2021

Example 17 Not in Syllabus - CBSE Exams 2021

Example 18 Important Not in Syllabus - CBSE Exams 2021

Example 19 Important Not in Syllabus - CBSE Exams 2021

Example 20 Not in Syllabus - CBSE Exams 2021

Example 21 Not in Syllabus - CBSE Exams 2021

Example 22 Not in Syllabus - CBSE Exams 2021

Example 23 Important Not in Syllabus - CBSE Exams 2021

Example 24 Not in Syllabus - CBSE Exams 2021

Example 25 Important Not in Syllabus - CBSE Exams 2021

Example 26 Not in Syllabus - CBSE Exams 2021

Example 27 Important Not in Syllabus - CBSE Exams 2021

Example 28 Not in Syllabus - CBSE Exams 2021

Example 29 Not in Syllabus - CBSE Exams 2021

Example 30 Not in Syllabus - CBSE Exams 2021

Example 31 Not in Syllabus - CBSE Exams 2021

Example 32 Not in Syllabus - CBSE Exams 2021

Example 33 Not in Syllabus - CBSE Exams 2021

Example 34 Not in Syllabus - CBSE Exams 2021

Example 35 Not in Syllabus - CBSE Exams 2021

Example 36 Not in Syllabus - CBSE Exams 2021

Example 37 Not in Syllabus - CBSE Exams 2021

Example 38 Not in Syllabus - CBSE Exams 2021

Example 39 Not in Syllabus - CBSE Exams 2021

Example 40 Not in Syllabus - CBSE Exams 2021

Example 41 Important

Example 42 Important

Example 43 Important

Example 44

Example 45 Important Not in Syllabus - CBSE Exams 2021

Example 46 Important

Example 47 Important

Example 48 Important

Example 49

Example 50

Example 51 Important You are here

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.