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) −y     (b) y (c) 25y   (d) 9y

This question is inspired from Ex 5.7, 11 - Chapter 5 Class 12 - Continuity and Differentiability

### Transcript

Question 14 If y = 5 cos x β 3 sin x, then (π^2 π¦)/(ππ₯^2 ) is equal to: (a) βy (b) y (c) 25y (d) 9y y = 5 cosβ‘γπ₯β3 sinβ‘π₯ γ Differentiating π€.π.π‘.π₯ ππ¦/ππ₯ = (π(5 cosβ‘γπ₯β3 sinβ‘π₯ γ))/ππ₯ ππ¦/ππ₯ = (π(5 cosβ‘π₯))/ππ₯ β (π(3 sinβ‘π₯))/ππ₯ ππ/ππ = β 5 πππβ‘π β 3 πππβ‘π Again Differentiating π€.π.π‘.π₯ π/ππ₯ (ππ¦/ππ₯) = (π γ(β 5 sinγβ‘π₯ γβ 3cosγβ‘γπ₯)γ)/ππ₯ (π^2 π¦)/(ππ₯^2 ) = β(π(5 sinβ‘π₯))/ππ₯ β (π(3 cosβ‘π₯))/ππ₯ (π^2 π¦)/(ππ₯^2 ) = β 5 cosβ‘π₯ β 3 γ(βsinγβ‘γπ₯)γ (π^2 π¦)/(ππ₯^2 ) = β 5 cosβ‘π₯ + 3 sinβ‘π₯ (π^2 π¦)/(ππ₯^2 ) = β (5 πππβ‘π β 3 πππβ‘π) (π^π π)/(ππ^π ) = βy So, the correct answer is (A)