NTA Abhyas JEE Main2020MathematicsDifferential EquationsPractice
If y = f x satisfies the differential equation d y d x + y = sin x + cos x and f 0 = 2 , then lim x → ∞ f x - sin x is equal to
Options
- Ae
- B2
- C0
- D1
Correct answer
C. 0
Step-by-step solution
Given equation is a linear differential equation Integrating factor = e ∫ d x = e x So the equation is y e x = ∫ e x sin ⁡ x + cos ⁡ x d x = e x sin ⁡ x + C ⇒ f x = sin ⁡ x + C e - x Since f 0 = 2 ⇒ C = 2 Hence, f x = sin ⁡ x + 2 e - x ⇒ f x - sin ⁡ x = 2 e - x Therefore, lim x → ∞ ⁡ f x - sin ⁡ x = 0