Let [.] be the greatest integer function. If = 064 (x1/3 - [x1/3] )dx, then 1 0 ( 2 6 + 6 )d is equal to .
Answer
36
Solution
064 x1/3dx = 34 [x4/3 ]064 = 34 256 = 192
[x1/3] = k for k3 x < (k+1)3:
064 [x1/3]dx = 0(1) + 1(8 - 1) + 2(27 - 8) + 3(64 - 27)
= 7 + 38 + 111 = 156
= 192 - 156 = 36
Let f( ) = 2 6 + 6 ; f has period , so 036 f = 36 0 f
0 f = 0 /2 2 + 2 6 + 6 d (putting + 2 in the second half)
6 + 6 = 1 - 3 2 2 = 1 - 34 2 2
0 /2 d 1 - 34 2 2 = 0 /2 d 2 + 14 2 ( = 2 )
= 0 /2 4 2 d 4 + 2 = [2 -1 2 ]0 /2 =
1 036 f( ) d = 1 36 = 36
Answer: 36