# Ex 1.3 , 6

Last updated at March 11, 2017 by Teachoo

Last updated at March 11, 2017 by Teachoo

Transcript

Ex1.3 , 6 Show that f: [−1, 1] → R, given by f(x) = 𝑥𝑥 + 2 is one-one. Find the inverse of the function f: [−1, 1] → Range f. (Hint: For y ∈ Range f, y = f(x) = 𝑥𝑥 + 2 , for some x in [−1, 1], i.e., x = 2𝑦1 − 𝑦 ) f(x) = xx+2 Check one-one f(x1) = 𝑥1𝑥1 + 2 f(x2) = 𝑥2𝑥2 + 2 Putting f(x1) = f(x2) 𝑥1𝑥1 + 2 = 𝑥2𝑥2 + 2 x1(x2 + 2) = x2(x1 + 2) x1x2 + 2x1 = x2x1 + 2x2 x1x2 – x2x1 + 2x1 = 2x2 0 + 2x1 = 2x2 2x1 = 2x2 ⇒ x1 = x2 Hence, if f(x1) = f(x2) , then x1 = x2 ∴ f is one-one Finding inverse f(x) = 𝑥𝑥 + 2 Putting f(x) = y y = 𝑥𝑥 + 2 y(x + 2) = x yx + 2y = x yx – x = –2y x(y – 1) = –2y x = −2𝑦 𝑦 −1 x = −2𝑦 −1−𝑦 + 1 x = 2𝑦 1 − 𝑦 Let g(y) = 2𝑦 1 − 𝑦 where g: R → [−1, 1] Thus, g is inverse of f Inverse of f = g(y) = 𝟐𝒚 𝟏 − 𝒚

Chapter 1 Class 12 Relation and Functions

Ex 1.2, 5
Important

Ex 1.2 , 10 Important

Example 23 Important

Example 25 Important

Ex 1.3, 3 Important

Ex 1.3 , 6 Important You are here

Ex 1.3 , 8 Important

Ex 1.3 , 9 Important

Ex 1.3 , 13 Important

Ex 1.3 , 14 Important

Ex 1.4, 11 Important

Misc 3 Important

Misc. 4 Important

Misc 14 Important

Misc 18 Important

Class 12

Important Question for exams Class 12

- Chapter 1 Class 12 Relation and Functions
- Chapter 2 Class 12 Inverse Trigonometric Functions
- Chapter 3 Class 12 Matrices
- Chapter 4 Class 12 Determinants
- Chapter 5 Class 12 Continuity and Differentiability
- Chapter 6 Class 12 Application of Derivatives
- Chapter 7 Class 12 Integrals
- Chapter 8 Class 12 Application of Integrals
- Chapter 9 Class 12 Differential Equations
- Chapter 10 Class 12 Vector Algebra
- Chapter 11 Class 12 Three Dimensional Geometry
- Chapter 12 Class 12 Linear Programming
- Chapter 13 Class 12 Probability

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.