NTA Abhyas JEE Main2020MathematicsIndefinite IntegrationPractice
The least value of n   n ∈ N , such that the function f n , x = ∫ n cos ⁡ n x d x satisfies f n , π 2 = - 1 , is (given, f n , 0 = 0 )
Options
- A3
- B4
- C5
- D6
Correct answer
A. 3
Step-by-step solution
Given function is f n , x = n ⋅ sin n x n + c As f n , 0 = 0 ⇒ c = 0 ∴ f n , x = sin n x If f n , π 2 = - 1 , we have sin n π 2 = - 1 ⇒ n = 3 , 7 , 11 , … … ∴ n m i n = 3