JEE Main202131 Aug 2021Evening ShiftMathematicsDefinite IntegrationActual
If x is the greatest integer ≤ x , then π 2 ∫ 0 2 sin π x 2 x - x [ x ] d x is equal to :
Options
- A2 ( π + 1 )
- B4 ( π - 1 )
- C2 ( π - 1 )
- D4 ( π + 1 )
Correct answer
B. 4 ( π - 1 )
Step-by-step solution
Let, I = π 2 ∫ 0 2 sin π x 2 x - x [ x ] d x I = π 2 ∫ 0 1 sin π x 2 x - x [ x ] d x + π 2 ∫ 1 2 sin π x 2 x - x [ x ] d x I = π 2 ∫ 0 1 sin π x 2 x 0 d x + π 2 ∫ 1 2 sin π x 2 x - 1 1 d x I = π 2 ∫ 0 1 sin π x 2 d x + π 2 ∫ 1 2 sin π x 2 x - 1 d x I = π 2 ∫ 0 1 sin π x 2 d x + π 2 x ∫ 1 2 sin π x 2 d x - ∫ 1 2 d d x x ∫ 1 2 sin π x 2 d x d x - π 2