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

Class 12
Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

## (a) 2       (b) π/2 + √3 (c) π/2    (d) The least value does not exist

### Transcript

Question 20 The least value of the function π(π₯) = 2 πππ  π₯ + π₯ in the closed interval ["0," π/2] is: (a) 2 (b) π/2 + β3 (c) π/2 (d) The least value does not exist Let f(π₯)="2 πππ  π₯ + π₯" Finding fβ(π) πβ(π₯)=π(2 cosβ‘π₯ + π₯)/ππ₯ =β2 sinβ‘π₯+1 Putting fβ(π)=π β2 sinβ‘π₯+1=0 2 sin π₯=1 sin π₯=1/2 β΄ x = π/π Since we are given closed interval ["0," π/π] Letβs check value of f(x) at 0, π/π and π/π f(0) = 2 cos 0 + 0 = 2 Γ 1 + 0 = 2 f(π/π) = 2 cos π/π + π/π = 2 Γ β3/2 + π/π = β3 + π/π f(π/π) = 2 cos π/π + π/π = 2 Γ 0 + π/π = π/π Since value of f(x) is lowest at x = π/π So, the correct answer is (C)

#### Davneet Singh

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.