If - /2 /2 8 2 x dx (1+e x ) (1+ 4x )= + e(3+2 2), where , are integers, then 2+ 2 equals :
Answer
8
Solution
x -x: I= - /2 /2 8 2 x e x (1+e x ) (1+ 4x )dx; add the two forms
2I= - /2 /2 8 2 x1+ 4xdx I=8 2 01 dt1+t4 ( x=t)
11+t4= 12 [ 1+ 1t2 (t- 1t )2+2- 1- 1t2 (t+ 1t )2-2 ]
I=4 2 [ 1 2 -1 t- 1t 2- 12 2 t+ 1t- 2t+ 1t+ 2 ]01
=4 (0+ 2 )-2 ( 2- 22+ 2-0 )
=2 -2 (3-2 2)=2 +2 (3+2 2)
= =2 2+ 2=8
Answer: 8