NTA Abhyas JEE Main2020MathematicsArea Under CurvesPractice
Let f x be a continuous and positive function and the area bounded by y = f x , the x -axis and the lines x = 0 and x = a is 4 a 3 + sin ⁡ a sq. units a > 0 . If f π 2 = k π 2 , then the value of k is
Correct answer
3
Step-by-step solution
Given area is ∫ 0 a f x d x ∴ ∫ 0 a f x d x = 4 a 3 + sin a Differentiating w.r.t. a , we get f a = 12 a 2 + cos a ⇒ f π 2 = 3 π 2 ⇒ k = 3