NTA Abhyas JEE Main2020MathematicsIndefinite IntegrationPractice
The integral I = ∫ e x cos e x x d x = f x + c (where, c is the constant of integration) and f ln π 4 2 = 2 . Then, the number of solutions of f x = 2 e ∀ x ∈ R - 0 is equal to
Correct answer
0
Step-by-step solution
Given integral is I = ∫ e x cos ⁡ e x x d x Let e x = t ⇒ e x 2 x d x = d t ∴ I = 2 ∫ cos ⁡ t d t = 2 sin ⁡ t + c = 2 sin ⁡ e x + c ∴ f x = 2 sin ⁡ e x which has range = - 2,2 Hence, f x = 2 e has no solution