JEE Main202227 Jul 2022Evening ShiftMathematicsContinuity and DifferentiabilityActual
Let f x = 2 + x - x - 1 + x + 1 , x ∈ R . Consider S 1 : f ' - 3 2 + f ' - 1 2 + f ' 1 2 + f ' 3 2 = 2 S 2 : ∫ - 2 2 f x d x = 12 Then,
Options
- Aboth S 1 and S 2 are correct
- Bboth S 1 and S 2 are wrong
- Conly S 1 is correct
- Donly S 2 is correct
Correct answer
D. only S 2 is correct
Step-by-step solution
Given f x = 2 + x - x - 1 + x + 1 ,   x ∈ R ⇒ f x = - x , x < - 1 x + 2 , - 1 ≤ x < 0 3 x + 2 , 0 ≤ x < 1 x + 4 , x ≥ 1 ⇒ f ' x = - 1 , x < - 1 1 , - 1 < x < 0 3 , 0 < x < 1 1 , x > 1 ∴    f ' - 3 2 + f ' - 1 2 + f ' 1 2 + f ' 3 2 = - 1 + 1 + 3 + 1 = 4 i.e. S 1 is incorrect. Now ∫ - 2 2 f x d x = ∫ - 2 - 1 f x d x + ∫ - 1 0 f x d x + ∫ 0 1 f x d x + ∫ 1 2 f x d x = - x 2 2 -