NTA Abhyas JEE Main2020MathematicsDefinite IntegrationPractice
Given f x = x | x | for x ≤ - 1 x + 1 + 1 - x for - 1 < x < 1 - x | x | for x ≥ 1 , where [.] denotes the greatest integer function. If I = ∫ - 2 2 f x d x , then 3 I =
Correct answer
8
Step-by-step solution
f x = - x 2   for   x ≤ - 1 ,   f x = 1   for   - 1 < x < 0 , f x = 2   for   x = 0 , f x = 1   for   0 < x < 1   and f x = - x 2   for   x ≥ 1 ⇒ f x is even ∴ I = 2 ∫ 0 2 f x   d x = 2   ∫ 0 1 f x   d x + 2 ∫ 1 2 f x   d x = 2 ∫ 0 1 1   d x + 2 ∫ 1 2 - x 2 d x = - 8 3 ∴   | 3 I |   =   | - 8 |   = 8