The value of - /6 /6 ( + 4x111 - (|x| + /6) )dx is equal to:
- 8
- 4
- 2
- 6
Answer
(2) 4
Solution
The denominator is an even function of x, so 4x111 - (|x| + /6) is odd and its integral over [- /6, /6] is 0.
I = - /6 /6 1 - (|x| + /6)dx = 2 0 /6 dx1 - (x + /6)
Put x + /6 = t: I = 2 /6 /3 dt1 - t
= 2 /6 /3 1 + t 2 tdt = 2 /6 /3( 2 t + t t) dt
= 2 [ t + t ] /6 /3
= 2 [( 3 + 2) - ( 1 3 + 2 3 ) ]
= 2 [( 3 + 2) - 3] = 4
Answer: (2)