The value of 9 09 [ 10xx+1 ]dx, where [t] denotes the greatest integer less than or equal to t, is .
Answer
155
Solution
g(x)= 10xx+1 increases from 0 to 9 on [0, 9] g [0, 3]
g=1 10x=x+1 x= 19; g=2 10x=4x+4 x= 23
[ g ]=0 on [0, 19 ), 1 on [ 19, 23 ), 2 on [ 23, 9 )
I=9 [1 ( 23- 19 )+2 (9- 23 ) ]
=9 [ 59+ 503 ]=5+150=155
Answer: 155