CBSE Class 12 Sample Paper for 2022 Boards (MCQ Based - for Term 1)

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Question 5 - CBSE Class 12 Sample Paper for 2022 Boards (MCQ Based - for Term 1) - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Last updated at April 16, 2024 by

Find the intervals in which the function f given by f (x) = x2 – 4x + 6 is strictly increasing:
(a) (-∞, 2) ∪ (2,∞)   (b) (2,∞)
(c) (-∞, 2)                (d) (-∞, 2] ∪ (2,∞)  

This question is inspired from - Example 10 - Chapter 6 Class 12 Application of Derivatives

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Transcript

Question 5 Find the intervals in which the function f given by f (x) = x2 – 4x + 6 is strictly increasing: (a) (−∞, 2) ∪ (2,∞) (b) (2,∞) (c) (−∞, 2) (d) (−∞, 2] ∪ (2,∞) f(𝑥) = 𝑥2 – 4𝑥 + 6 Calculate f’(𝒙) 𝑓’ (𝑥) = 2𝑥 – 4 Calculate f’(𝒙) = 0 2𝑥 – 4 = 0 2𝑥 = 4 𝑥 = 4/2=2 Hence 𝑥 = 2 divide real line into 2 disjoint intervals. Plotting points on number line Hence. f is strictly increasing in interval (2 , ∞) So, the correct answer is (b)

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.